simple crater

simple crater

[′sim·pəl ′krād·ər]
(geology)
A meteorite impact crater of relatively small diameter, characterized by a uniformly concave-upward shape and a maximum depth in the center, and lacking a central uplift.
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Lonar crater is a 1.88-km diameter simple crater formed entirely within the Deccan traps (a large volcanic province consisting of many layers of basalt flows), making it a useful analogue for small craters on other terrestrial planets and the Moon.
Arizona's Meteor Crater--also known as Barringer Crater, after the Philadelphia mining engineer who began studying the site in 1902--is the best-preserved terrestrial example of such a so-called simple crater.
The Moon * March 2009 Highlighted feature Size (miles) Description (A) Copernicus (L5 58 Large complex crater (B) Carlini 6 Simple crater (C) Plato (L83) 68 Large lava-filled crater L numbers refer to Charles Wood's Lunar 100 list; see SkyandTelescope.com/lunar100.
The 13-kilometer-wide, 2.7-km-deep crater Mosting A (L61 in the Lunar 100, introduced in the April issue, page 113, and online at SkyandTelescope.com/ observing/objects/moon/) is a prime example of a simple crater. It has a circular outline, a bright inner wall, and a parabolic shadow that falls across the bottom of the crater.
The Lunar 100 L Feature name Significance 5 Copernicus Archetypal large complex crater 61 Mosting A Simple crater close to center of Lunar near side See Sky & Telescope: April 2004, page 113, or point your Web browser to SkyandTelescope.com/observing/objects/moon.
This simple crater is probably best known for the famous ray that crosses it and seems to continue across Lacus Mortis and on to eastern Mare Frigoris.
The Ariadaeus Rille (named for the small simple crater at its eastern end) is a classic example of the flat-floored, parallel-walled straight rille.
Simple craters have steep walls and small, flat floors, looking like they were turned out by a lathe.
Craters between 25 km and 130 km in diameter usually have a central peak and in proportion to diameter, the excavation zone is much shallower than smaller simple craters. Instead of excavating a proportional amount of material as in smaller craters, here some of the impact force has been absorbed.
LRO's topographic profile reveals that Moltke is about 0.8 mile deep, so its depth-to-diameter ratio is 0.2--very typical of such simple craters. A transition to shallower ratios occurs when lunar craters reach diameters of about 10 to 15 miles.
But these simple craters, as typified by Lalande A near the center of the near-side disk, are too small to reveal much detail telescopically.
There are thousands of similar simple craters on the Moon, all small and with hard-to-see interiors.