English: NASA/JPL/University of Arizona
Cones and Inflated Lava Flows
ESP_030192_2020 Science Theme: Volcanic Processes
http://hirise.lpl.arizona.edu/ESP_030192_2020
https://www.wired.com/wiredscience/2013/01/space-photo-of-the-day-2/?pid=6342
A CTX image shows topographic cones in local depressions here. What are these and how did they form?
This image reveals "rootless cones," which form on lava flows that interact with subsurface water. They are in depressions because subsequent lava flowed around the base of the cones, then "inflated." Lava inflation is a process where liquid is injected beneath the solid (thickening) crust and raises the whole surface, often raising it higher than the topography that controlled the initial lava emplacement.
This scene is in Amazonis Planitia, a vast region covered by flood lava. The surface is coated by a thin layer of reddish dust, which avalanches down steep slopes to make dark streaks.
Written by: Alfred McEwen (audio by Tre Gibbs) (20 February 2013)
Acquisition date: 04 January 2013 Local Mars time: 3:14 PM
Latitude (centered): 21.965 degrees Longitude (East): 197.807 degrees
Range to target site: 288.0 km (180.0 miles) Original image scale range: 57.6 cm/pixel (with 2 x 2 binning) so objects ~173 cm across are resolved
Map projected scale: 50 cm/pixel and North is up Map projection: EQUIRECTANGULAR
Emission angle: 2.9 degrees Phase angle: 61.9 degrees
Solar incidence angle: 64 degrees, with the Sun about 26 degrees above the horizon Solar longitude: 238.2 degrees, Northern Autumn
For non-map projected products:
North azimuth: 97 degrees Sub-solar azimuth: 327.0 degrees
For map-projected products
North azimuth: 270 degrees Sub solar azimuth: 141.4 degrees