Page:The Moon (Pickering).djvu/59

Rh in shape the mark that a bullet might make in penetrating obliquely a somewhat viscous surface. Scattered among them are a number of smooth, rounded mounds, some circular and some elongated. Some of the latter look as if they would exactly fit into the spindle-shaped cuts. Similar cuts are found in Cassini, 7A [2.2, 3.5]. To the north and west of Copernicus are a series of irregular elongated markings formed in part of craterlets, and due perhaps to the escape of gases through the formerly viscous surface from a submerged crack or rill. Similar markings are found to the southeast of Schiller, 12B [2.4, 6.2]. A little over one diameter due east of Gassendi, 14E [2.0, 2.2], is a curious ring of isolated elevations surrounding a central peak. A little north of Cavalerius, 15A [2.4, 6.7], is situated a very striking black peak.

A series of well-marked parallel grooves, each groove several miles in width, forms a characteristic feature of certain portions of the Moon's surface. They are well seen to the southwest of Pallas, 7E [3.2, 7.3], and lie in a direction nearly northeast by southwest. They extend from somewhat to the north of Hyginus, 7E [2.1, 7.0], as far south as Albategnius, 8E [2.4, 1,9], and are well seen on both these plates, also upon 10E, where more than a dozen grooved valleys may be traced. A less marked series of parallel grooves lies southeast of Sinus Iridum, 11B [1.9, 3.1], and another near the south pole. They are evidently similar to the great grooved valley of Rheita, 4B [2.5, 6.3]. Several similar smaller grooved valleys occur in this immediate vicinity, and are described by Gilbert, who ascribes their origin to large meteorites which just grazed the surface of the Moon. I have found no evidence of the meteorites at the end of the grooves. Their origin is more probably due to wide subterranean cracks, which caused the surface to soften and sag into them. A connecting link between them and the rills is to be found one diameter west of Posidonius. It is not well shown on the photograph, but its position may be found on 3 B [3.1, 4.2]. It runs in a nearly north-and-south direction.

A large, nameless, ruined crater, 12E [0.9, 4.2], of oval shape, and exhibiting a curious spiral arrangement of supporting ridges, is to be found lying between Wurzelbauer and Heinsius. Although lava streams are seldom clearly defined upon the Moon, one may be seen where Wargentin, 14B [1.7, 6.2], overflowed its crater on the northeast, flooding the surrounding region. This overflow probably prevented the lava from rising higher in the adjoining crater [1.5, 6.3], north of Phocylades, [1.3, 6.5]. The interior of this nameless crater is on the same level as the surface of Wargentin and several hundred feet higher than the level in Phocylades proper.