Ismenius Lacus Quadrangle - Glaciers

Glaciers

Glaciers formed much of the observable surface in large areas of Mars. Much of the area in high latitudes, especially the Ismenius Lacus quadrangle, is believed to still contain enormous amounts of water ice. In March 2010, scientists released the results of a radar study of an area called Deuteronilus Mensae that found widespread evidence of ice lying beneath a few meters of rock debris. The ice was probably deposited as snowfall during an earlier climate when the poles were tilted more. It would be difficult to take a hike on the fretted terrain where glaciers are common because the surface is folded, pitted, and often covered with linear striations. The striations show the direction of movement. Much of this rough texture is due to sublimation of buried ice. The ice goes directly into a gas (this process is called sublimation) and leaves behind an empty space. Overlying material then collapses into the void. Glaciers are not pure ice; they contain dirt and rocks. At times, they will dump their load of materials into ridges. Such ridges are called moraines. Some places on Mars have groups of ridges that are twisted around; this may have been due to more movement after the ridges were put into place. Sometimes chunks of ice fall from the glacier and get buried in the land surface. When they melt and more or less round hole remains. On Earth we call these features kettles or kettle holes. Mendon Ponds Park in upstate NY has preserved several of these kettles. The picture from HiRISE below shows possible kettles in Moreux Crater.

• Moreux Crater moraines and kettle holes, as seen by HIRISE.

• Clanis and Hypsas Valles, as seen by HiRISE. Ridges are probably due to glacial flow. So water ice is under a thin layer of rocks.

• Tributary Glacier, as seen by HiRISE.

• Coloe Fossae Lineated Valley Fill, as seen by HiRISE. Scale bar is 500 meters long.

• Place where a lobate debris apron begins. Note stripes which indicates movement. Image located in Ismenius Lacus quadrangle. Lobate Debris Aprons have been shown to contain almost pure water ice covered over with a layer of rocky debris.

• Probable glacier as seen by HiRISE under HiWish program. Radar studies have found that it is made up of almost completely pure ice. It appears to be moving from the high ground (a mesa) on the right.

• Mesa in Ismenius Lacus quadrangle, as seen by CTX. Mesa has several glaciers eroding it. One of the glaciers is seen in greater detail in the next two images from HiRISE.

• Glacier as seen by HiRISE under the HiWish program. Area in rectangle is enlarged in the next photo. Zone of accumulation of snow at the top. Glacier is moving down valley, then spreading out on plain. Evidence for flow comes from the many lines on surface. Location is in Protonilus Mensae in Ismenius Lacus quadrangle.

• Enlargement of area in rectangle of the previous image. On Earth the ridge would be called the terminal moraine of an alpine glacier. Picture taken with HiRISE under the HiWish program.

• CTX context image showing location of next HiRISE image (letter A box).

• Possible moraine on the end of a past glacier on a mound in Deuteronilus Mensae, as seen by HiRISE, under the HiWish program. Location of this image is the box labeled A in previous image.

• Remains of glaciers, as seen by HiRISE under the HiWish program.

• Remains of a glacier after ice has disappeared, as seen by HiRISE under HiWish program.