# Where on Mars are the known craters or collapse features with very high depth/diameter ratio?

Figure 1 of this article about craters and collapse features on Mars with high depth/diameter ratios shows that ratios higher than 0.2 are exceptional.

This presentation of the Program of the Second MSL Landing Site Workshop about possible landing sites in Sinus Meridiani shows an image of a "crater" that is 2.4 km wide and 750 meters deep !

Because the ratio of this feature is more than 0.3 and it has no clear rim, it is very likely that this is not an impact crater at all.

Are there more known features on Mars with such a very high depth/diameter ratio ?

• Does this feature in the image have a name? – BlueCoder Sep 12 '18 at 11:44
• @BlueCoder Could not find a name at planetarynames.wr.usgs.gov/nomenclature/AdvancedSearch so i think you could propose a name. – Conelisinspace Sep 12 '18 at 13:14
• The concept of a depth to diameter ratio is an interesting idea. I'm still trying to get my head around it. In a way it's an analogous of the average/overall slope angle of the wall of the "crater". This angle will largely be dictated by the properties of the wall rock (ie, by way of example, loose sand will have a shallow angle, very competent basalt will have a high angle). Generally this angle will be the angle of rest for the rock type. The other things that will affect the depth of an impact crater will be the hardness & competency of of the host rock. – Fred Sep 12 '18 at 17:17
• Taking some rough measurements from the screen. I get a diameter of 110 mm & a wall width of 30 mm (on the rightmost side). With a depth to diameter ratio of 0.3 the depth is 33 mm (0.3 x 110). Get the arc tan of (33/30) gives a wall angle of 47 degrees. – Fred Sep 12 '18 at 17:20
• @Fred Thank you for your comments. Maybe we will find a similar, much smaller feature and then we could place a transparent dome on it to keep it warm.:) (I should have added "at Fred" to my earlier comment on Sept. 12) – Conelisinspace Sep 24 '18 at 8:09