Physical Characteristics and Processes of 100-m-scale raised-rim depressions (RRD's) on Earth: application to Mars

100-m-scale raised-rim depressions (RRD's) of various origins are found on both Earth and Mars. We define RRD's morphologically, as circular, elongate, or irregularly shaped forms having raised rims encircling lower elevation terrain. Terrestrial RRD's include phreatomagmatic cones, basaltic ring structures, collapsing or collapsed pingos, rimmed kettle holes, and mud volcanoes. Terrestrial experience commonly guides extra-terrestrial investigations, so these terrestrial types of RRD's are also the types that have been commonly hypothesized for RRD's on Mars, although other origins (e.g., secondary impacts onto deflating surfaces) are also likely on Mars. Identifying the origins of Martian RRD's is useful because different types of RRD's imply different geological processes (and therefore have different astrobiological connotations). Being of a similar shape and size in plan view, different types of RRD's are often difficult to classify remotely. However, each of these types of RRD's has specific geomorphic characteristics that can be remotely assessed. Based on terrestrial studies, we present guidelines of a scale applicable to new current and near-future spacecraft data to aid in identifying various types of RRD's on Mars. This presentation will entail discussion of selected types of RRD's, including their geneses, morphologic characteristics, distributions, and common geological associations. The RRD's are grouped according to primary origin, ie., volcanic, sedimentologic, and other. In summary, we present some guidelines for classifying RRD's on Mars.