Data

Most of the photographs used for geologic mapping were acquired by the departing spacecraft during the first pass (Mercury I). The Mercury II encounter provided no usable images of the map area; two low-oblique photographs suitable for geologic mapping were acquired during the third flyby on March 17, 1975 (Davies and others, 1978, p. 31). No stereoscopic phtographic pairs are available for the Bo

The Bach region encompasses the south polar part of Mercury poleward of lat 65 degrees S. About half of the region was beyond the terminator during the three Mariner 10 encounters and hence not visible. The entire mapped area was covered by near-vertical photography from the second encounter, and the eastern part, from long 15 degrees to about 110 degrees, was covered by oblique photography from t

The Beethoven quadrangle is located in the equatorial region of Mercury, in the center of the imaged area. Most pictures of the quadrangle were obtained at high sun angles as the Mariner 10 spacecraft receded from the planet. Images in the northeastern part of the quadrangle are very poor to unusable. Another difficulty in mapping is the poor match in topographic bases between Beethoven and adjace

The Galindo quadrangle (V-40; centered at lat 12.5 degrees S., long 255 degrees) was geologically mapped at 1:5,000,000 scale under the Venus Data Analysis and Venus Geologic Mapping Programs as part of a project focused on the study of venusian geologic terrains containing assemblages of coronae, arachnoids, and novae; these are enigmatic circular features perhaps related to hot-spot volcanism. M

The Magellan spacecraft orbited Venus from August 10, 1990, until it plunged into the venusian atmosphere on October 12, 1994. Magellan had the objectives of (1) improving knowledge of the geologic processes, surface properties, and geologic history of Venus by analysis of surface radar characteristics, topography, and morphology and (2) improving knowledge of the geophysics of Venus by analysis o

The Sappho Patera quadrangle (V-20) of Venus is bounded by 0 degrees and 30 degrees East longitude, 0 degrees and 25 degrees North latitude. It is one of 62 quadrangles covering the entire planet at a scale of 1:5,000,000. The quadrangle derives its name from Sappho Patera, a large rimmed depression (diameter about 225 km) lying on top of a shield-shaped mountain named Irnini Mons. Sappho, a noted

The Lavinia Planitia quadrangle (V-55) is in the southern hemisphere of Venus and extends from 25 degrees to 50 degrees south latitude and from 330 degrees to 360 degrees longitude. It covers the central and northern part of Lavinia Planitia and parts of its margins. Lavinia Planitia consists of a centralized, deformed lowland flooded by volcanic deposits and surrounded by Dione Regio to the west

The Tharsis quadrangle lies within the sparsely cratered hemisphere (Carr and others, 1973) of Mars. Its geology is dominated by young volcanic features, including both circular constructs and lava plains; little evidence of primitive densely cratered terrain remains. Included are three of the four largest shield volcanoes in the Tharsis province, Olympus Mons, Ascraeus Mons, and Pavonis Mons, t

Mars presents two different terrains, a highly cratered surface that lies mostly in the southern hemisphere and sparsely cratered plains that lie mostly in the northern hemisphere. The cause of the dichotomy is a still unsolved fundamental problem of Martian geology, analogous to the problem of continents and ocean basins in terrestrial geology. The present features of the plains in particular r

The Oxia Palus quadrangle contains three distinct geologic provinces: (1) an elevated cratered plateau that occupies three-fourths of the quadrangle and is similar to much of the southern hemisphere of Mars; (2) the low, relatively featureless Chryse Planitia in the northwest corner; and (3) a complex province of chaotic terrain and immense channels or valleys that divides the plateau an determina

The Phoenicis Lacus quadrangle (named Lake of the Phoenix by Schiaparelli, 1877) includes some of the largest geologic features recognized on the terrestrial planets. Arsia and Pavonis Montes, (South Spot and Middle Spot of Marine 9) rise 18 and 17 km, respectively, above the surrounding plateau to an elevation large volcanoes Ascraeus and Olympus Montes, located outside the quadrangle to the nor

The Coprates quadrangle lies to the east of the Tharsis volcanic complex and the Noctis Labyrinthus tectonic complex. To the north are the plains of Lunae Planum, to the east the vast patches of chaotic terrain and the large sinuous channels that trend northward into Chryse Planitia. On the southwest is the Thaumasia Fossae region of tectonically deformed cratered terrain, to the southeast, the A