OMR

Sun Elevation: -14.5'

Distance: -2724 km

A circumferential plain, probably a melt sheet, fills the sloped basin floor between the outer Montes Rook (oMR, 620 km) and the northeastern sector of Montes Cordillera (MC, 930 km). Hartwig (H,79km), just to the east of Schluter (S, 89 km) and just a little smaller, has been covered with Orientale ejecta. Schluter's age is assigned to the Late Imbrian Period because it is free of ejecta from the Orientale event, but was there before the period of mare emplacement, which has extruded into its northern floor.

L04-195H2 (left), L04-187H2 (center), and L04-181H2 (right)

Sun Elevation: -14.5'

Distance: -2724 km

Mare Orientale (MO) covers the central floor of the Orientale Basin, surrounded by the inner Montes Rook (iMR, 480 km), the outer Montes Rook (oMR, 620 km), the circumferential melt sheet beyond the outer Montes Rook, and Montes Cordillera (MC, 930km) beyond the melt sheet. The circumferential melt sheet has received its own intrusion of mare lava in places such as Lacus Autumnis (LA). The shores of mare flows such as Lacus Autumnis, Lacus Veris (LV), and Mare Orientale rise around their boundaries, a sign that the mare has risen above its current level and then subsided as it cooled.

L04-195H1 (left), L04-187H1 (center), and L04-181H1 (right)

Sun Elevation: -14.5'

Distance: -2724 km

In the southeastern sector of the interior of the Orientale Basin, the melt sheet between the outer Montes Rook (oMR) and Montes Cordillera (MC) widens. Patterns of stress cracks (sc) appear on the melt sheet on the slope leading from the inner Montes Rook down to Mare Orientale. A fine radial pattern appears on the circumferential melt ring in this sector, not particularly correlated with the deeper pattern outside Montes Cordillera. Rimae Pettit (RP, 450km), radial narrow depressions, extend from the mare across the Montes Rook and across the melt sheet. These features may be a result of the formation of Montes Rook, which may have occurred shortly after the primary impact event, as a result of rebound of the compressed material in the transient crater. Rimae Focas (RF, 100km), narrow depressions between the inner and outer Montes Rook, are filled with lava. Pettit (P, 35 km) and Nicholson (N, 38 km) may have come from a pair of impactors. Fryxell (F, 18 km) and Shuleykin (Sh, 15 km) have landed on the inner Montes Rook.

Sun Elevation: -15'

Distance: -3036 km

This shows the southern sector of the outer Montes Rook, the south from Wright (W, 39km), the young crater of the Eratos-wide circumferential melt sheet, and Montes Cordillera. The thenian Period and the more eroded crater Shaler (S, 48km), of start of the deep trough called Vallis Bouvard (VB) extends the Late Imbrian Period.

Distance: -3036 km

Sun Elevation: -15

L04-194H2 (left),L04-186H2 (center), and L04-180H2 (right)

The prominent trough and ridge system of Vallis Bouvard 55km) has impacted the ridge on the western boundary of (VB) continues southward, crossing this entire image. The Vallis Bouvard. Vallis Inghirami (VI) is to the east of Vallis length of Vallis Bouvard is estimated to be 284 km. Baade (B, Bouvard and extends for 148 km.

L04-194H1 (left),L04-186H1 (center),and L04-180H1 (right) Sun Elevation: -15° Distance: ~3036km

Vallis Bouvard (VB) and Vallis Inghirami (VI) change their shape here; the continuous valleys of the northern images break into irregular patterns of secondary craters, no longer really valleys. The radial pattern of the continuous ejecta blanket of Orientale thins out in this image, terminating near Pingre (P, 88 km). Pingre itself has escaped the heavy blanket, but has received a powdery dusting of finely divided plains forming material from Orientale. Pingre has landed on the floor of the Pingre-Hausen Basin (PH, 300km), formed in the pre-Nectarian Period.

LO4-193H3

Sun Elevation: 10.31°

Distance: 3557.30 km c

LO4-193H3

Sun Elevation: 10.31°

Distance: 3557.30 km

The smooth patch (sp) appears to have been deposited as molten material. It may be an exposed part of the floor of the Mendel-Rydberg Basin or may be Orientale ejecta. This may be a suitable landing site for examination of the minerals in this area, but higher resolution photography would be required. Baade (B, 55 km) is an example of an elliptical crater, an indication that its impactor arrived at a low elevation. The alignment of its major axis with Orientale ejecta suggests that it is a secondary crater, formed by a block ejected from Orientale.

LO4-193H2

Sun Elevation: 10.31°

Distance: 3557.30 km

LO4-193H2

Sun Elevation: 10.31°

Distance: 3557.30 km

The crater Hausen (H, 167 km) is of the Erastosthenian period. It has deposited some of its ejecta on the floor of its Nectarian neighbor Bailly (B, 287 km). This juxtaposition provides an opportunity to study the differences in texture between impact features of these two periods. Note the relative frequency of craters on the floors, rims, and ejecta blankets of the two features. Also note the collapse of terraces in the wall of Bailly's rim.

Drygalsky (D, 149 km) can be seen to be pre-Nectarian, ing the large central peak. Not enough detail is visible in as indicated by the many craters of considerable size that Boltzmann (B, 76 km) to establish its age. have impacted it. Yet it retains its basic shape, includ-

Chapter 13

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