| Comments |
| Lunation | 1075 |
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| Phase | Waxing Gibbous |
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| Age | 12.22d |
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Distance
Light Time
(from earth) | 378,343 km
s |
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| Elongation | ° |
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| % Illuminated | 86.8% |
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| Morning Terminator Colongitude (λ E) | 53.6° |
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| Evening Terminator Colongitude (λ W) | 233.6° |
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| Libration in Latitude | -6° 11' |
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| Libration in Longitude | -6° 3' |
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| Magnitude | -11.1 |
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| Angular Size | 31.58' |
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| Altitude | 58° 15' |
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Virtual Moon Atlas graphic |
My main goal for tonight was to see if I could see any of the men, women and animals in the moon. I accomplished that and a good bit more.
The image of the Man in the Moon is a pareidolia. Wikipedia says a pareidolia is
- Pareidolia
- (pronounced /pærɪˈdoʊliə/) is a psychological phenomenon involving a vague and random stimulus (often an image or sound) being perceived as significant.Common examples include seeing images of animals or faces in clouds, the man in the moon, and hearing hidden messages on records played in reverse. The word comes from the Greek para- ("beside", "with", or "alongside"—meaning, in this context, something faulty or wrong (as in paraphasia, disordered speech)) and eidolon ("image"; the diminutive of eidos ("image", "form", "shape")). Pareidolia is a type of apophenia.
I have never seen any of the images in the Moon so am giving it another try tonight while the Moon is full.
Full Moon | This is my reference image so I know what is under the drawings in the other images. |
Man Carrying Sticks with Dog | I saw the man but could not make out the sticks. |
Man in the Moon | I don't see all of the detail depicted in this image but get the concept. His right eye and that side of his mouth were partially obscured by the terminator. |
Woman | I got the hair and the cheek but had trouble with the features of the face and didn't see Tycho and its rays at all. |
Face | This one was easy although the nose was a lottle obscure. His right eye was partially inthe terminator. |
Rabbit | I could make out the ears, head and hump of the back of the rabbit but that is about all. Maybe on a Full Moon nightwhen I can see his lower body I would have better luck. |
| images from Wikipedia |
| Terminator |
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| In Shadow | Feature | In Sunlight |
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| | J. Herscel | >>> |
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| | Harpalus | >>> |
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| | Sharp | >>> |
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| | Mairan | >>> |
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| <<< | Montes Agricola | >>> |
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| | Vallis Schroter | >>> |
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| | Herodotus | >>> |
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| | Aristarchus | >>> |
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| | Marius | >>> |
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| <<< | Reiner | |
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| | Hansteen | >>> |
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| | Billy | >>> |
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| | Mersenius | >>> |
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| <<< | Schicard | >>> |
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| | Schiller | >>> |
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| | Segner | >>> |
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| | Zucchus | >>> |
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| | Betinus | >>> |
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I started off the night with some naked-eye observing of the Moon to identify as many of the images on the surface of the Moon as I could.
We spent a lot of time tonight in the southern highlands around Schiller and in Oceanus Procelarum near Aristarchus. I can’t remember a time when the southern highlands has looked as clear and was as easy to navigate as it was tonight.
Schiller looks strange sitting down there near the south lunar pole. It is long and thin with a bulge near it’s center while everything around it is round. Peter speculated that it was caused by multiple impacts and I said that if that was the case then the impacts must have occurred simultaneously as there was no indication of the walls of any of them on the crater floor. Peter found some lines in the surface that suggested to him a larger old crater surrounding and nearly tangent to Schiller. I could follow his lines although we didn’t always agree on exactly where they went. I had brought the Moon Observer’s Guide with me so got it out to see what Grego has to say. Schiller, a prominent, somewhat elongated walled plain (171 x 71 km), comes into view in the southwest. Possibly a line of three joined craters (perhaps resulting from a simultaneous multiple impact), the broader, smoother southern plain of Schiller narrows in the north, where a couple of larhe ridhes cross the floor from north to south. Schiller itself lies on the northeasterb margins of a large but unnamed (350 km diameter) multiringed badin, unofficially designated the Schiller Annular Plain. This feature is visible toward the end of day ten and during day eleven. Looking at the inner ring below Schiller I had the impression that it was over top of a pair of tangent young craters. It looked to me as though cookie dough had been draggled onto a cold surface and hardened there. It does not appear to be continuous but rather three sections of draggle. Peter bumped the magnification up to 237x and for me this impression was even stronger. That would mean that first came the Schiller Annular Plain then Schiller then the two young craters and lastly this mound that we are attributing to an inner rim of the plain and that can’t be. We looked it it an a lunar atlas app on Peter’s iPhone and there the draggles appear to be interrupted by the later-occurring craters.
 detail from Geologic Lunar Atlas (Southern Hemisphere plate) graphic
Map Key
- Nc
- CRATER MATERIAL YOUNGER THAN NECTARIS BASIN BUT OLDER THAN IMBRIUM BASIN -- Few rim or interior textures visible except in largest craters; queried where could be units pNc or Nbc
BASIN MATERIALS
- Ioc
- MATERIAL OF ORIENTALE-BASIN SATELLITIC CRATERS -- Grouped in clusters and chains peripheral to Orientale basin and in some outlying areas.
Interpretation: Secondary impact craters or Orientale basin; queried where could be primary craters
- Ioho
- Outer facies -- Discontinuous deposits adjacent to Orientale secondary craters (mapped and unmapped) commonly having basin-radial ridges and grooves.
Interpretation: Mostly ejecta formed by closely spaced secondary impacts
PROBABLE BASIN-RELATED MATERIALS
- Ip
- PLAINS MATERIAL - Light-colored, smooth, mostly flat-surfaced deposits having superposition relations and crater densities indicating Imbrian age.
Interpretation: Primary and secondary ejecta of Orientale and Imbrium
The large-scale map in the corner of that plate names the basin as the Schiller-Zucchius Basin which is contained within the Orientale Basin.
 detail from Geologic Lunar Atlas (Southern Hemisphere plate)
 detail from LAC plate 125
 NASA LOPAM image
(NW at top of image)
The chart collar contains the following explanatory text:
BASIN MATERIALS
Most lunar impact excavations larger than 260 km in diameter and some smaller ones possess one or more raised inner rings and so are called multiring basins (Hartmann and Kuiper, 1962). Other circular features this size and larger probably also originally had multiple rings, but the inner rings are now obscured. Many terra materials mapped here can be identified with specific basins, and the remainder are also believed related to basins or craters. Formation of two large, ancient (pre-Nectarian) basins (South Pole-Aitken and Australe) raised the hightest mountains, three Nectarian basin impacts and the later Orientale basin impact outside the map area deposited extensive material within it; and other pre-Nectarian, Nectarian, and Imbrian basins in and outside the area contributed to its geomorphic and stratigraphic framework.
RING IDENTIFICATION AND DATING OF BASINS
The largest and oldest basin so far documented on the Moon is South Pole-Aitken (Stuart-Alexander, 1978), also called Big Backside basin or Aitken-Backside basin. The basin rim is defined by a discontinuous mountain ring 2200 km (Stuart-Alexander, 1978) to 2500 km (this report) in diameter. The larger figure is based on an interpretation that massifs (map symbol pNbm) and adjacent rugged material (map symbol pNbr) between lat 75° S., long 40° W. and the unphotographed zone are part of the rim, and that other massifs and rugged material entirely on the far side constitute a second ring 250 to 500 km inside the rim. Alternatively, all the basin massifs and rugged basin material may constitute a very broad rim whose mean diameter would be about 2200 km. The rugged basin material as far north as lat 63° S. on the near side may also be part of the rim flank. The near-side massifs were discovered by Earth-based telescopic observations, and their connection with a large basin beyond the lunar limb was predicted by Hartmann and Kuiper (1962). The South Pole-Aitken basin is also expressed as a giant depression detected by Zond 6 and 8 photographic altimetry (Rodinonov and others, 1971, 1977) and Apollo laser altimetry (Wollenhaupt and Sjorgren, 1972; Bills and Ferrari, 1975; Kinsler and others, 1975). We estimate the basin center to be located at about lat 56° S., long 180°. Numerous small mare patches, partly localized in superposed basins and craters, occupy the basin inside the inferred inner ring.
At least four other basins centered in the map area are also pre-Nectarian in age. Planck, Poincare, and Schiller-Zucchius (“basin near Schiller” of Hartmann and Kuiper, 1962) are small, double-ring basins identified as pre-Nectarian on the basis of degraded superposed craters. The fourth, Australe, is named for many small, discontinuous patches of mare material collectively known as Mare Australe. The circular pattern of the mare patches and an enclosing arcuate chain of massifs near long 120° E led to recognition of Australe as a basin (Stuart-Alexander and Howard, 1970). This chain apparently indents the rim of South Pole-Aiken, a relation which suggests that Australe is the younger basin; exceptionally large massifs in this chain may have been uplifted by impacts. Additional massifs and elevated tracts of rugged basin material and other units appear to define two interior Australe rings.
Four additional pre-Nectarian basins have been tentatively identified. A single ring about 700 km in diameter delineates a heavily cratered probable basin here named Mutus-Vlacq according to the convention of designating basins after supposed (unrelated) features (Wilhelms and El-Baz, 1977). This postulated rim accounts for small mounds of basin massif material (map symbol pNbm) and other elevated basinlike terrain (map symbol pNb) near lat 62° S., long 35° E., and the basin may have acted as a catchment for an otherwise puzzling concentration of Nectarian plains materials (map symbol Ntp). The smaller Sikorsky-Rittenhouse and Amundsen-Ganswindt basins show traces of inner rings (not mapped), but their identity as basins and their ages are uncertain because of burial by deposits from the Schrodinger basin. Parts of their postulated rings -- especially those of Sikorsky-Rittenhouse (“unnamed A” basin of Hartmann and Wood, 1971, later withdrawn from the list of basins by Wood and Head, 1976) -- could instead be part of the Sout Pole-Aitken basin. Finally, an indistinct possible basin named Pingre by Hartmann and Kuiper (1962) and Pringre-Hausen in this report underlies deposits of the crater Hausen and of the basins Orientale, Bailly, and Mendel-Ryberg.
Three basins centered in the map area are believed to be Nectarian in age -- younger than the Nectaris basin and older than the Imbrium basin on the northern near side. The three differ greatly in degree of degradation. An indistinct, large basin, here named Mendel-Rydberg, was called the “SE limb basin” by its discoverers Hartman and Kuiper (1962), who identified on telescopic photographs two of the three rings mapped ere. The nearby Bailly basin is smaller and younger. Both Bailly and Mendel-Rydberg are severely degraded as a consequence of burial by deposits from Orientale and the crater Hausen but are thought Nectarian in age because no pre-Nectarian craters appear to be supported. The Schrodinger basin is younger still, and its deposits cover much of the map area. The density of superposed craters too small to map here (<20 km) suggests an age of late Nectarian, but this fresh-appearing basin could be lower Imbrian as no definite Nectaran craters are superposed. The inner ring consists of rugged crags similar to those of lunar central peaks (Hartmann and Wood, 1971) and is believed related in origin to such peaks although its exact formative process is uncertain (Hodges and Wilhelms, 1978). The other, terraced ring resembles the rims of craters (Howard and others, 1974, fig. 4) and must similarly be the limit of the excavated cavity modified by slumping.
INTERPRETATION OF CIRCUM-BASIN DEPOSITS AND SATELLITIC CRATERS
Deposits from basins outside the map area dominate more than half of its northern border zone. Emplacement processes of basin deposits have been deduced from the well-exposed, well-photographed Orientale materials. The inner facies of the Hevelius Formation (map symbol lohi) is a continuous, strongly lineated, apparently thick deposit that extends back to the Orientale basin rim (Montes Cordillera) north of the region and that, accordingly, must contain much primary basin ejecta. This deposit apparently flowed along the surface at least part of the distance from the rim, for parts of it piled up as transverse ridges against the southeast wall of the crater Inghirami and other obstacles (McCauley, 1968; Scott and others, 1977). The relatively smooth, nonlineated facies of the Hevelius formation (map symbol lohn) is gradational with the coarsely textured inner facies and in part forms raised lobes bounded by distinct scarps (Moore and others, 1974, figs. 6, 7) that suggest flowage of a viscous, fluidlike material.
Secondary impact apparently emplaced most deposits beyond the inner and nonlineated facies of the Hevelius Formation and beyond comparable, though less well preserved materials of other basins (Moore and others, 1974; Oberbeck and others 1974, 1975; Morrison and Oberbeck, 1975; Oberbeck, 1975; Wilhelms, 1976). Satellitic craters of Orientale (map symbol loc) so closely resemble secondary impacts of large lunar craters (Offield, 1971; Wilhelms and McCauley, 1971; Oberbeck and Morrison, 1974; Wilhelms, 1976) that their identity as Orientale basin secondaries seems certain. Basin-radial ridges and smooth deposits commonly lie on the distal side of the secondary crater and constitute a discontinuous unit called the outer facies of te Hevelius Formation (Scott and others, 1977(; most of these deposits presumably consist of secondary ejecta. East of long 20° E. are corresponding, though less fresh, features of the Nectaris basin, indluding secondary craters (part of map unit Nbc) andridged deposits (Janssen Formation, Stuart-Alexander, 1971). The Nectarian basin deposits (map symbol Nbl) and clustered secondary craters (map symbol Nbc) near the map border between long 142° and 176° W. are related to the Apollo basin centered 300 km nort of the area. We have mapped the Apollo-related units as Nectarian based on their morphology ut the basin may instead be pre-Nectarian (Stuart-Alexander, 1978.
Other probably secondary craters throughout the map area, though not closely satellitic to basins, have been traced to their sources by orientation. Secondaries of Schrodinger (Nectarian) are easily identified as far as three basin diameters from its rim by linear, groovelike shapes and the concentration in few azimuthal directions that characterize the basin. A few probable Nectarian secondary craters in the vicinity of the Apollo deposits are more closely radial to the distant Hertzsprung basin, 1400 km north (lat 1° N., long 129° W.), than to Apollo. Numerous large chains east of the crater Clavius, also mapped as Nectarian basin secondaries, are radial to the distant Humorum basin (lat 24° S., long 39° W.) and may be parts of its secondary field although their nature is problematic. Finally, outliers of the large field of secondary impact craters of the Imbium basin (map symbl Iic) occur in the north part of the map area.
PROBABLE BASIN-RELATED MATERIALS
Additional units interpreted as basin related occur among and beyond the secondary craters and lineated deposits. The inner, nonlineated, and outer facies of the Hevelius Formation grade in places into smooth-surfaced plains-forming material of Imbrian age that occupies depressions (map symbol Ip). Gradations of the smooth plains material with primary and secondary basin materials suggest that the plains material here consists of ejecta and not volcanic material, as has een proposed for some plains (for example, Wilhelms and McCauley, 1971; Neukum, 1977). Similar plains of Imbrian age that are distant from the Orientale basin may be ejecta of Imbrian-basin secondary craters or of large Imbrian primary craters. Nectarian terra-mantling and plains material (map symbol Ntp) is probably similar in origin to these Imbrian deposits for it is concentrated around Nectarian basins (Nectaris, Schrodinger, Mendel-Ryberg, and Apollo), large craters (Clavius), and satellitic and distant secondary craters of Nectarian basins including those tentatively ascribed to Humorum. Age assignment of plains and terra-mantling materials depends partly upon crater counts made on photographs of uneven quality, so that some patches mapped as Imbrian could be Nectarian.
The outer facies of the Hevelius Formation grades outward into less heavily mantled terrain with fewer lineations and pits that is mapped as composite units -- Imbrian and Nectarian with fewer terra (map symbol INt) where the units visible under the Orientale textures are mostly Nectarian, and Imbrian and pre-Nectarian terra (map symbol IpNt) where the underlying material is mostly pre-Nectarian. Much terrain outside te distinctive materials of Nectarian basins, though mostly lacking conspicuous lineations and pits, also seems subdued and a mantle that is gradational with the Nectarian basin materials and accordingly is mapped as Nectarian and pre-Nectarian terra (map symbol NpNt). Visibility of textures and therefore mapping of many lunar material units depends both on photographic quality and degree of degradation. For example, the outer facies of the Hevelius Formation and the Orientale-related composite units may be more extensive than mapped, especially on the far side where photographs are poorest. Also, time-related degradation has probably blurred Nectarian textures that once resembled those of Orientale, so that the well-defined basin-related province is less extensive relative to the probable basin-related province (fig.2) for the Necctarian system than for Orientale. The degradation process has proceeded even further among pre-Nectarian units, where the rugged basin material (map symbol pNbr) and even more poorly defined, generally low-lying unit called pre-Nectarian terra material (map symbol pNt) occupy the positions of the much more distinctive and varied younger basin units that they presumably once resembled. Contributions to the pre-Nectarian terra unit from the various pre-Nectarian basins and craters are not distinguished on this map because of inadequate photography and exposure.
Two more distinctive but less extensive units may also be related to basins although their origin is uncertain. The exposure of grooved material (map symbol IpNg) in certain areas near long 160° E. and the better exposures immediately to the north (Stuart-Alexander, 1978) are antipodal to the Imbrium basin and have been interpreted as the products of the impact of converging Imbrium ejecta (Moore and others, 1974) or shaking induced by seismic waves from Imbrium (Schultz and Gault, 1975). Most fractured crater floors (map symbol Ifc), the other areally restricted unit, are probably products of extensive floor uplift, and common phenomenon in and near basins (Pike, 1971; Schultz, 1976), but some peripheral to the Orientale deposits could be Orientale impact melt, as observed elsewhere in similar positions (Moore and others, 1974).
CRATER MATERIALS
Primary impact craters with a complete range in ages dot the map area, as they do all lunar highlands. The materials of these craters are still perceived much as described on earlier maps such as that by Wilhelms and McCauley (1971).
The usual Imbrian crater Antoniadi (lat 69.5° S., long 172° W.), 150 km wide, deserves special mention for two reasons. First, it is ringed by an unusually extensive and dense array of secondary impact craters (map symbol Isc). Second, it has booth a central peak and an inner ring of peaks, making it transitional between craters and multiring basins (Hartmann and Wood, 1971; Hodges and Wilhelms, 1978).
In summary, thegeology of the terra can be accounted for by a succession of large and small impacts that excavated basins and craters, deposited the ejecta where it cratered and redistributed the preimpact terrain. Basins were also favorable sites for subsequent internal activity, such as crater-floor uplift and mare volcanism.
MARE AND OTHER DARK MATERIALS
Although, in general, the near side of the Moon has more extensive mare material than the far side, the reverse is true in this southern area. Except near the east limb, that part of the near side within the map area is nearly devoid of mare material; whereas the far-side part contains dozens of mare patches. This concentration results from depressions afforded by the Australe and South Pole-Aitken basins and the smaller basins and craters superposed on them.
Three age groups of mare material have been mapped (two in fig. 2), each of which represents stratigraphically complex units with a range of ages. The oldest group (map symbol Im1) was early recognized as exceptionally old for lunar mare material (Stuart-Alexander and oward, 1970). It is older than many upper Imbrian crater materials (map symbol Ic2) and than all known mare materials of the central near side. It is lighter in color than most other mare units and is gradational in color and crater density with the terra and plains materials. The intermediate mare material mapped here (map symbol Im2) substantially overlaps typical near-side material in age, although its full age range has not been determined. The distinction between mare units is clear over most of Mare Australe but can be made only tentatively in the poorly photographed area in the South Pole-Aitken basin. The youngest unit (map symbol Elm) is partly or entirely Eratosthenian. Small mare domes (map symbol Imd) and similar swellings that may be domes are mantled terra (map symbol Imd?) also mapped, as are small patches of dark mantling material (Id) surrounding their apparent source vents in the Schrodinger basin.
A few large wrinkle-ridge structures traverse part of Mare Australe but wrinkle ridges and fault grabens are rare in the map area, in contrast with their abundance in and near the large nearside lunar maria. This distribution supports an inference that most nonimpact compression and extension of the lunar crust relate to crustal loading by mare basalts (Solomon and Head, 1979).
GEOLOGIC HISTORY
The detectable history of the region begins with the largest event inferred from visible landforms on the Moon, the impact that raised the massive South Pole-Aitken rim, excavated most of the far-side part of the map area, and probably covered the near-side part with excavated debris. A second large impact formed the adjacent Australe basin, and smaller pre-Nectarian impacts excavated at least three basins (Poincare, Planck, and Schiller-Zuccius), possibly four others tentatively identified, and perhaps still others that have been obscured. The Nectarian Period began with the formation of the Nectaris basin, which is centered outside the map area but strongly influenced it by covering and cratering many pre-Nectarian craters and basin deposits. Later in Nectarian time, the Apollo and Humorum impacts also deposited materials and formed secondary craters in the north part of the area, and the Mendel-Rydberg, Bailly, and Schrodinger basins and the large crater Clavius were formed within it. Schrodinger, with its distinctive, linear secondary-crater chains and pronounced double-ring structure, strongly affected the appearance of the southern far side. In the Imbrian Period, ejecta from the distant Imbrium basin formed scattered secondary craters, Orientale basin deposits blanketed a huge region on the west limb including the Mendel-Rydberg and Bailly basins, and Orientale ejecta formed many secondary craters beyond this blanket. Mare volcanism left still-visible traces in the lowlands of the South Pole-Aitken and Australe basins beginning about the time of the Orientale impact, continuing through the Imbrian Period, and locally extending into the Eratostenian. Impact events, which in Imbrian time produced the crater-basin Antoniadi and other large craters, continued at a low rate through the Eratosthenian and Copernican Periods.
 Geologic Lunar Atlas (Southern Hemisphere plate) graphic
Somewhere over near the terminator and down toward the equator we saw a couple of isolated peaks that had shadow behind them. One of the shadows was very long and narrow and as the night prohressed we watched its apex emerge from the terminator as the sun rose and its shadow grew shorter and the terminator moved away from it.
Montes Agricola were coming out of the shadow of the terminator. The eastern end of the range had a bright white SW face with shadow beind it. Another portion of the range came out of the terminator at nearly right angles to the brighter section running to te SW. Beneath Montes Agricola we noted three bright, white peaks, the largest of which is named Mons Herodotus (Herodotus χ) and it 5 km in diameter. The upper two peaks are identified as Undifferentiated Materials - Characteristics
- Exposed on isolated hills surrounded by other materials in areas of rough topography. Albedo intermediate to very high and like unit Cs
- Interpretation
- Crustal material or other materials. May include some Fra Mauro Formation
while Mons Herodotus is classified as slope material.- Characteristics
- Albedo very high. Present mainly on interior crater slopes. Also found on hills
- Interpretation
- Talus and bedrock associated with slopes at the angle of repose; freshly exposed by sliding and slumping
.png) Lunar Topophotomap sheet 38B2s1(50)
Vallis Schorteri was visible snaking above Heroditus. It is composed of material of the Copernican-Eratosthenian age described as - Characteristics
- CEvh, hummocky member. Materials of rolling to hummocky terrain. Some areas of CEvh exhibit rays, but fewer rays than adjacent mare materials. Albedo low to very low but generally higher than that of CEvs
- Interpretation
- Volcanic materials. Absence of superposed rays on many surfaces suggests units are partly Copernican in age. Superposition on Procellarum Group indicated units are post-Imbrian
with the internal walls of slope material (described above).
 detail from LAC plate 38
 detail from Geologic Lunar Atlas plate I-527
.png) detail from Lunar Topographic Orthophotomap (plate LRO-38B3 Freud)
The collar of I-527 says
GENERAL INFORMATION
The surface of the Moon is heterogeneous. Local surfaces can be classed on the basis of telescopic observations into units, each having a limited range of physical properties such as topography, visible under low illumination, and albedo, the reflectivity under full-Moon illumination. The properties of such surface units are considered to represent properties of underlying materials, so that surface units corresponding to underlying rock units which are analogous to the rock-stratigraphic formations of terrestrial geology. These rock units are arranged in order of relative age and grouped into time-stratigraphic units by application of the concepts of superposition and intersection, and by their apparent modification of properties with time. Following terrestrial convention, the major time-stratigraphic units are designated systems; the three systems recognized to date are the Imbrian, Eratosthenian and Copernican. The type localities of the systems are in the vicinity of Mare Imbrium (Shoemaker, 1962; Shoemaker and Hackman, 1962).
GEOLOGIC SUMMARY
INTRODUCTOION
The Seleucus quadrangle lies in the northwestern part of Oceanus Procellarum, a large mare of irregular shape in the western part of the earthside hemisphere of the Moon. Material of the mare occupies most of the quadrangle. Craters ranging from 1 to 44 km and ridges rise above the mare. In the east-central part of the quadrangle, the Aristarchus plateau (informal name) slopes gently westward and merges with the surrounding surface of Oceanus Procellarum. The plateau contains the largest known lunar sinuous rille, Vallis Schorteri. The plateau is also known for its reddish color and light absorption properties (Wood, 1912), and areas where occasional bright reddish glows have been seen (Greenacre, 1965).
STRATIGRAPHY
Volcanism and impact cratering have contributed to the formation of the surgace features of the quadrangle throughout its interpretable geologic history. Many materials present can be roughly classified into the three major time-stratigraphic systems, although assignment to systems is somewhat uncertain except in the type areas, and sharp boundaries between systems do not exist. A few units cannot be placed in a system, such as units IpIc and IpIu. Correlations, age relations, and interpretations for the units are discussed below.
Photographic evidence collected by the U.S.S.R.’s Luna 9 (Lebedinskiy, 1966) and the United States’ Ranger series and Surveyor I (California Inst. Technology, 1966, pls. B-88, P-12; Jaffe and others, 1966; U.S. Natl. Aeronautics and Space Adm., 1966) has shown that the lunar surface in other areas has been significantly modified and altered on a fine scale by impact cratering. Preliminary evakuationof photographic evidence from the U.S.S.R.’s Luna 13, which landed December 24, 1966 in the Seleucus quadrangle suggests that such modification also has occurred here (Anderson, 1966). Thus, unmodified materials of the units mapped in the Seleucus quadrangle may not occur at the surface but at a depth which depends on the degree of modification. This depth may range from a few millimeters to tens of meters or more. The degree of modification should increase with the age of the material, local concentrations of rays, and proximity to large impact craters.
Pre-Imbrian or Imbrian Systems. -- A lower age limit of the oldest materials in the quadrangle -- the cratermaterials (unit IpIc) which form the rim of the crater Eddington and the undifferentiated materials (unit IpIu) -- cannot be established, because they are not in contact with the Fra Mauro Formation, the unit that defines the base of the Imbrian System. However, the deformed and modified appearance of the crater Eddington suggests that it is very old and is probably pre-Imbrian. That part of unit IpIu which is nearly contiguous with the Fra Mauro Formation in the adjacent Aristarchus region may be Fra Mauro, and Fra Mauro is shown in the cross section near the Aristarchus region. Units IpIc and IpIu are generally surrounded, embayed, or filled by mare material and, therefore, are older than mare material.
Imbrian System. -- Crater rim, wall floor, and peak materials (unit Ic and its subdivisions) of the craters Briggs,Seleucus, and Schiaparelli are placed in the Imbrian System. These materials are partly covered with mare material and the craters appear fresher and less deformed and modified than pre-Imbrian craters elsewhere on the Moon. The craters Briggs and Seleucus were probably produced by the impacts of large bodies from space, because radial ridges and a hummocky ejecta blanket can be seen along the crater flanks. The peculiar internal annular structure and apparently smooth flacks of Schiparelli are, however unusual, so that a volcanic origin is possible.
Mare material, which covers most of the Seleucus quadrangle, is divided into two units. The first unit, mare material of the Procellarum Group (unit Ipm), as a higher albedo and density of supposed rays than te second, designated dark mare material of the Procellarum Group (unit Ipmd). The Procellarum Group in the type area is in the Imbrian System by definition; however, the dark mare material may be superposed on the lighter mare material and, although tentatively assigned to the Imbrian, may be partly Eratosthenian or partly Copernican (McCauley, 1967). At least one patch of dark mare material embays the Copernican crater Lichtenberg (discussed later). Mare materials probably represent volcanic ash flows, ash falls, or lava flows.
Imbrian and Eratosthenian Systems. -- A small area in the northeast part of the quadrangle is questionably assigned to the Harbinger Formation IElh), which was originally defined in the Aristarchus region (Moore, 1965). This formation may be entirely if Imbrian age in the Seleucus quadrangle, but mapping in the Aristarchus region has shown that it is part contemporaneous with and partly younger than mare material. Although the contiguous material in the Aristarchus region was assigned to the Fra Mauro formation and not Harbinger Formation, subsequent studies have shown it may e Harbinger. He materials of the Haringer Formation are probably volcanic (Moore, 1964). In the Seleucus quadrangle. Topography suggests that the materials are associated with a partly buried rille about the width of Vallis Schroteri.
Eratosthenian System. -- In the Eratostenian System are crater materials and volcanic materials. The crater materials (unit Ec and its subdivisions) occur in and around craters that are younger than the mare material but have no associated rays. The radial ridges of the superposed rim material extend out over the mare material, and it any rays were once present they have been degraded and modified and are no longer visible. Most of the craters may be the result of impacts, but some, especially those on mare ridges, may be of volcanic origin. Volcanic material makes up the smooth undularing Marius Group (unit Em) (McCauley, 1967), which occupies only a small area in the southeastern part of the Seleucus quadrangle.
Eratosthenian and Copernican Systems. -- The Vallis Schroteri Formation (unit CEv) occurs on the Aristarchus plateau. This formation, first mapped in the adjacent Aristarchus region (Moore, 1965), is divided in the Seleucus quadrangle into five units; hummocky member, dome material, cone-crater material, dark smooth member, and low-rimmed crater material. This formation is unusually red and has a lower albedo than mare material. In general the dark smooth member and low-rimmed crater material are younger than the others. Relative ages of units not in contact are inferred from apparent amount of supposedly ray material. Where superposition relations are observed, these units, with the possible exception of the hummocky member in one place, appear to overlie the Precellarun Group. With this possible exception, the materials formed during the Eratostenian and Copernican Periods.
The hummocky member (CEvh) has a higher albedo that the smooth member and is overlain by some rays. This unit appears to be superposed on mare material along the northwest edge of the Aristarchus plateau. Along the southwest margin of the plateau, the age relations between the hummocky member and mare material are not clear. Although the mare material there has the greater density of supposed rays, parts of the hummocky member could be contemporaneous with mare material. A small patch of the hummocky member extends into the adjacent Aristarchus region where it was not previously mapped. The member probably consists of a thin layer of volcanic material mantling a pre-existing hummocky surface.
Dome material (CEvd) forms convex-upward domical surfaces which have a small crater near the apex; core-crater material (CEvc) forms the rims of surrounding flanks of irregular high-rimmed craters. These materials are probably volcanic. For example, the cone crater Aristarchus R is at the apex of an elliptical hill probably composed of volcanic flows and ejecta, and the double done crater Herodotus D has coarse lobes extending down its flanks which probably reperesent lava flows; the lobes are too coarse to be the radial ridges and hummocks of an impact crater the size of Herodotus D (7 km in diameter). Some material from Herodotus D extends out upon mare material on the north edge of the plateau. Materials of cone ctaters and domes generally have more superposed rays that dark-smoothmaterial and are thus generally older.
Material of the dark-smooth member (CEvs) is superposed on material of the hummocky member and is younger. Only a few areas of the dark smooth member have superposed rays and the member may therefore be of Copernican age. Patches of this member are superposed on mare material of the Procellarum Group (unit Ipm) along the north flanks of the Aristarchus plateau. A small parch of the dark smooth member extends into the adjacent Aristarchus region where it was not previously mapped. The dark smooth member probably represents volcanic ash falls and ash flows or lava flows.
In general, low-rimmed crater material (unit CEvl) is unrayed and is superposed on hummocky material. Some of te larger low-rimmed craters are associated with the dark-smooth member and are contemporaneous with it. Some low-rimmed craters along the northwest edge of the Aristarchus plateau are apparently the source of material of the dark-smooth member that occurs on the mare surface and on the adjacent hummocky member.
The diverse morphologies, distribution, and age relations of materials maring up the Vallis Schroteri Formation suggests that the Aristarchus plateau is a volcanic field with a long and comples history characterized by diverse volcanic processes.
Copernican system. -- Copernican crater materials (unit Cc and its subdivisions and unit Csc) are scattered across the quadrangle; these bright materials and the rays surrounding them are superposed on many of the units discussed above. The rays and hummocky ejecta blankets around the large craters suggest that the craters were produced by impacts. Secondary craters (unit Csc) are probably also of impact irigin, because they are associated with rays from larger craters and have ejecta plumews radial to the parent crater or parallel to the rays that are clearly related to the parent crater.
Dark mare material (unit Cmd) occurs in the northwest part of the map area. This material has covered the ejecta and rays of Copernican crater Lichtenberg (unit Ccr) along the crater’s southeast flanks. Thus, this dark mare material is classed as Copernican. A few craters are superposed on this material, and another may be partly buried by even younger material. This dark mare material, which covers thousands of square kilometers, can best be ascribed to volcanism. Since this dark material is Copernican some areas of dark mare material assigned to the Procellarum Group (Ipmd) might be Copernican instead of Imbrian.
Sinuous rille (rima) material (unit Csr) is exposed in Vallis Schroteri on the Aristarcus plateau and extends into the Aristarchus region, where it terminates within the Cobra Head Formation. Vallis Schroteri may be a graven or a channel produced by the flow of volcanic material.
LINEATIONS AND FAULTS
Four sets of lineations are present in the Aristarchus plateau. The most conspicuous set, which is radia to the Imbrian basin, trends N. 40° -60°l E. Two other well developed sets trend N. 30° -40° W. These lineations are expressed by ridges, scarps, and rilles. The fourth set, which trends north-south, is expressed by some rilles. Displacenents have occurred along many of the lineations throughout the history of the Aristarchus plateau. An additional lineament tending about N. 75° E. may be present near and parallel to the southern contact of unit Cmd.
Further east we saw the drowned crater Prinz and Montes Harbinger and east of tem Delisle and Diophantus. MontesnDelisle appeared farther away from the crater of the same name than depicted on Peter’s S&T Field Map of the Moon. Dropping south from Diophatus Mons Vinogradov is slightly west of Euler.
Moving up to the juncture of Sinus Roris, oceanus Procellarum and Mare Imbrium, but at the western edge of Mare Imbrium, we saw Mons Gruithuisen Delta and Mons Gruithuisen Gamma. They look like blisters out on the mare with very smooth, rounded surfaces. Each is 20 km in diameter.
 detail from LAC plate 23
 detail from Geologic Lunar Atlas plate I-805
The Geologic Lunar Atlas has dome material listed under Volcanic (?) Landform Materials and describes them thusly:
- Characteristics
- Material of large, high (>1600 m) domes (Gruithuisen γ and δ) in southeast part of map area, and smaller domes mostly near east margin of Oceanus Procellarum. Albedo high. Gruithuisen domes have smooth to hummocky, gently rounded crests and steep hackly sides which apparently overlap mare basalts and structures in the mare (rille, depression, and ridge). Marian T, a nearly circular dome with group of summit craters, possibly embayed by mare basalt (Em). Queried where may be hill or unitIth
- Interpretation
- Volcanic cumulo-domes composed of viscous felsic lava. Eratosthenian age suggested by superposition on Imbrian Mare and possible embayment by Eratosthenian mare.
Tne I-805 collar says:
GEOLOGIC SUMMARY
SETTING
The Rumker quadrangle, in the northwest quadrant of the Moon, is adjacent to the western rim of the multi-ring Imbrium basin and to Sinus Iridum, a large I220 km diameter mare-filled crater. Both of these great depressions were probably formed by impact, as indicated here and elsewhere on the Moon by the characteristic form, distribution, and texture of surrounding materials and structures. The Imbrium basin and Imbbrium crater were filled by mare materials during the Imbrian and Eratosthenian Periods. In this quadrangle, the widespread ejecta blanket of the Imbrium basin, as well as the basin’s concentric ridges and mountain rings, has largely been buried by terra materials of mixed origin and by ejecta from Iridum and numerous small inpact craters. These materials, together with some terra units of probably volcanic origin, make up the highland terrain. Mare materials of Oceanus Procellarum cover part of this westward-sloping highland shelf and separate it from the Rumker Hills, an isolated plateau surrounded by the mare. No visible discontinuity distinguishes mare materials of Oceanus Procellarum from those in the Imbrium basin, both of which contain several units having similar albedo and color. Parts pf the mare are very dark and smooth and appear relativfely young, and parts of the terra contain many diverse landforms of Imbrain and younger age that appear to be volcanic. This region may therefore have been more active internally during the late stages of lunar history tham many others on the near side.
GEOLOGIC UNITS
The relative ages of units are determined by superposition and transaction relations and, less definitively, by morphologic and other criteria such as topographic sharpness, crater density, albedo, and thermal response at eclipse. Where possible, all units are assigned to the lunar stratigraphic column, as proposed by Shoemaker (1962), Shoemaker and Hackman (1962) and Wilhelms (1970). Materials are grouped into five categories according to their physical characteristics, probable mode of origin, or association with a major feature or event.
Imbrium basin materials comprise those units which by their age and distribution appear to be more closely associated with the formation of the Imbrium basin than with later volcanic, tectonic, or impact events. Materials exposed in fault scarps bounding tilted blocks marginal to the basin in the southeast highlands probably consist of Imbrium ejecta and pre-basin bedrock. The units are indistinguishable on the photographs and are mapped as one (IpIu). The Fra Mauro Formation is questionably identified in the Rumker Hills, but elsewhere the characteristic swirly texture of the Imbrium basin ejecta blanket as well as its hilly counterpart, the Alpes Formation, is not recognized. Instead, two terra units (Ith, Its) make up most of the highland terrain around the Imbrium basin. These units resemble subdued versions of both the Alpes and Fra Mauro Formations; thus they are interpreted as mantling units of unknown composition, origin, and thickness.
Iridum crater materials
The ejecta blanket of the Iridum crater extends about 250 km from the rim of Sinus Iridum just east of the quadrangle and provides a good marker horizon for this region of the Moon. It covers Imbrium basin materials and crater materials of early Imbrian age; superposition relations of younger units indicate that it is of middle Imbrian age. As with other large craters of impact origin, the rim materials of Iridum are subdivided into members by their texture, depositional patterns, and relief -- characteristics which also reflect the size, mode of transport, and velocity of the ejected or displaced materials. Within and beyond the continuous ejecta blanket are numerous craters and clusters of overlapping craters having elongate asymmetric outlines whose orientation and deposition indicate secondary impacts generated by the Iridum event. The largest individual members of the Iridum secondary crater population are about 10 km in diameter. The ratio of macimum secondary crater diameter to that of the primary crater is thus about 1:22, about the same as tat around large craters like Copernicus or the Orientale basin.
Mare and light plains materials
Two mare units of the Erastosthenian and Imbrian age are distinguished in Oceanus Procellarum by their albedo, color, and density of small craters. Imbrian mare and plains materials fill small isolated depressions within the terra. Albedo and crater density apparently increase progressively with increasing age: the youngest mare unit (EmO is dark and smooth, whereas plains material (Ip) is light and highly pitted with small craters. Spectral feflectance (Whitaker, (1966) has also been useful for subdividing mare materials as color seems to be generally constant within individual units. Older units appear redder than younger ones, and the younger reflect more blue light. Although color may be related both to composition and to age, this concordance between color and relative age may indicate a progressive change in composition of the materials with time.
Imbrian craters more than 3 km across are much more numerous on terrae than on maria, whereas Eratosthenian and Copernican craters are about equally abundant on both types of terrain. The Imbrian craters are embayed by both mare units but, with one possible exception (Naumann G), Eratosthenian and younger craters are superposed on the mare. These relations are in accord with a latest Imbrian age of the oldest mare unit of the Copernican or late Eratosthenian age for the mare embaying the Eratosthenian crater. The paucity of partly buried craters or their outlines indicates that the mare materials (probably basalts) are thick enough to have completely covered most Imbrian craters and probably some pre-Imbrian craters as well.
Crater materials
The age of the craters here ranges from early Imbrian to Copernican. A progressive decrease in the abundance of older or younger craters on the terra probably reflects a declining flux of impacting meteorites with time. Except for numerous secondary craters from Iridum, most craters have morphologies and material associations suggestive of an internal origin and are discussed below.
Volcanic (?) landform materials
Aside from the extensive basalt flows in Oceanus Procellarum, many other features in themselves or by association with others reflect the operation of volcanic processes in this region. The Gruithuisen domes (ed) and some smaller similar domes mapped as the same unit resemble terrestrial cumulo-domes formed by extrusion of highly viscous lava (Holmes, 1965, fig. 229) In the Rumker Hills, plug-like forms which have arched and possibly penetrated to the surface are bordered in places by lobate scarps resembling lava-flow fronts. Unlike most upland areas, the Rumker Hills have a low albedo, comparable with that of the adjacent mare, and, like the mare, they are probably basaltic in composition or are mantled by basalt.
Within the mare in the southeast part of the quadrangle a series of small craters (Ech) separatd by mesa-like hills form a ling, somewhat sinuous chain resembling a string of beads. Most of these craters are rimless, or nearly so (unlike impact craters) and resemble depressions formed by carving along parts of a lava tube or by subsurface drainage of magma into fissures and subsequent collapse. In this respect, the crater chain probably represents an early and incomplete stage in the process of rille formation; individual depressions did not coalesce and develop into the winding, continuous, flat-floored valleys illustrated by Rima Sharp to the northwest.
Crater chains as well as several hills with summit craters or breached ramparts (Ihc) in the western mare have morphologic analogs in terrestrial volcanic fields (Scott and Trask, 1971). Craters with ringed floors (Icfr) are like those mapped elsewhere on the Moon (Trask and Tinley, 1966). An outstanding terrestrial example of this type pf crater occurs in the Mount Lassen volcanic province (Chapman and others, 1969, fig. 31-6). The floors of ringed craters as well as some domes (EIdc). This association of clustered domes with craters resembling terrestrial volcanoes suggeststhat the domes may be tholoids consisting of viscous lava like those that form steep-sided domes in the vents of some strato-volcanoes on Earth. Other features, such as chain craters (ch), lobate material (Il), and a smooth unit (Es) on the rim of the crater Marian, are also interpreted as volcanic and suggest that magmatic differentiation progressed farther here than elsewhere on the Moon.
STRUCTURE
The main rim of the Imbrium multi-ring basin is poorly defined here. It originally formed high mountains like those of the Carpathian, Apennine, and Caucasus around the other parts of the basin. These have subsided and been buried by mare basalts, Iridum crater ejecta, and other materials. The large ridges of the Montes Jura are more nearly concentric with the Iridum crater than with the Imbrium basin. Some of the high but subdued areas north of the Gruithuisen domes, however, may be remnants of an Imbrium rim. Major mare ridges and rilles (such as those of Rima Shap) within Oceanus Procellarum strike northwest to about latitude 40° -45° N., where their trends swing rather abruptly to the northeast into Sinus Roris. This change in direction roughly reflects the curvature of the Imbrium basin and suggests that the ridges and rilles owe their existence (at least in part) to faults and fractures concentric with the basin. The ridges may represent upwelling and solidification of basaltic material along fractures during late stages of mare extrusion, whereas the rilles, like some of the chain craters (Ech) previously discussed, are probably collapsed lave drainage channels.
Troughs and ridges radial to Sinus Iridum occur in the rim materials of the Iridum crater and within terra units. Some of these lineaments probably resulted from sculpturing of the terrain by missiles within the ejecta cloud. However, many crater chains (ch) parallel lineament directions and, as they occur on plains deposits, must have formed after the Iridum impact. It seems likely, therefore, that many linealents, as well as crater chains, have structural roots.
GEOLOGIC HISTORY
The extensive ejecta blanket produced y the large impact which formed the Iridum crater eradicated much of the geologic record in the Rumker quadrangle prior to middle Imbrian time. Thhe Fra Mauro (?) and Alpes Formations, which are characteristic of the earlier more widespread ejecta blanket around the Imbrium basin, were mostly buried y the Iridum crater naterials as well as other younger units such as hilly and smooth terra and the mare materials of Oceanus Procellarum.
Evidence for early Imbrian to Eratosthenain volcanism in the highlands is present (units Icfr, Ici, EIh, EIdc, Ed). The more extensive terra materials (Ith, Its) also may be partly of volcanic origin.) The Rumker Hills were formed by faulting, uplift, and the intrusion of large plug-like forms which may have locally arched the surface and penetrated it during the Imbrian and Eratosthenian Periods. During the latter part of the Imbrian Period, lava flows filled crater floors and depressions within the terra, forming the level plains (Ip) in this area. These initial flows were succeeded by larger volumes of darker materials, probably basalts, which filled great depressions and formed the maria of Oceanus Porcellarum, the Imbrium basin, and Iridum crater. A change in composition of the basalt flows with time is indicated by albedo and color variations. The later flows that probably formed in Eratosthenian time are darker and bluer.
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