Lobate debris apron

The floors of some channels show ridges and grooves that seem to flow around obstacles; these features are called lineated floor deposits or lineated valley fill (LVF). Like lobate debris aprons, they are believed to be ice-rich. Some glaciers on the Earth show such features. It has been suggested that lineated floor deposits began as LDAs. By tracing the paths of the curved ridges characteristic of LDAs, researchers have come to believe that they straighten out to form the ridges of LVF. Both lineated floor deposits and lobate debris aprons often display a strange surface formation called brain terrain because it looks like the surface of the human brain. File:Wikifrettedctxp22.jpg|Wide CTX view showing mesa and buttes with lobate debris aprons and lineated valley fill around them. Location is Ismenius Lacus quadrangle. File:WikiESP 020769 2225fretted.jpg|alt=Close-up of lineated valley fill (LVF), as seen by HiRISE under HiWish program Note: this is an enlargement of the previous CTX image.|Close-up of lineated valley fill (LVF), as seen by HiRISE under HiWish program. This is an enlargement of the previous CTX image. File:Wikifrettedctxpo5.jpg|alt=Wide CTX view of mesa showing lineated valley fill and lobate debris apron (LDA). Both are believed to be debris-covered glaciers. Location is Ismenius Lacus quadrangle.|Wide CTX view of mesa showing lineated valley fill and lobate debris apron (LDA). Both are believed to be debris-covered glaciers. Location is Ismenius Lacus quadrangle. File:Wikifretesp 027639 2210lda.jpg|Close-up of lobate debris apron from the previous CTX image of a mesa. Image shows open-cell brain terrain and closed-cell brain terrain, which is more common. Open-cell brain terrain is thought to hold a core of ice. Image is from HiRISE under HiWish program. File:25246brainseroding.jpg|Closed-cell brain terrain, as seen by HiRISE under the HiWish program. This type of surface is common on lobate debris aprons, concentric crater fill, and lineated valley fill. File:Htalk23815 2215lvfclose.jpg|Open and closed-cell brain terrain, as seen by HiRISE, under HiWish program. Reull Vallis, pictured below, displays these deposits. Sometimes the lineated floor deposits show a chevron pattern, which is further evidence of movement. The picture below taken with HiRISE of Reull Vallis shows these patterns. == Recent observations ==

Recent analyses of the Nereidum Montes (~35–45°S, ~300–330°E), and Phlegra Montes (NNE–SSW, between latitudes 30–52°N) mountain ranges of Mars have revealed terrains rich in viscous flow features (VFFs), a cyro-geomorphological group of which lobate debris aprons are a sub-class. In a 2014 study, 11,000 VFFs have been recorded between 40° and 60° in northern and southern latitudes, with a 2020 study identifying approximately 3,348 VFFs in the Nereidum Montes range. These LDAs were more extensive and older VFF features (hundreds of Ma) in the range, with the vast majority located in impact craters and surrounding massifs. Studies have estimated that LDAs could reach from tens of meters up to in thickness, with anywhere from of overlying regolith preventing sublimation. Late Amazonian glaciation may have occurred in the mid-latitudes due to water-ice emplacement from higher latitudes. This glaciation may have occurred during high obliquity periods in Mars past. Some of these LDAs are overlain with another class of viscous ice flows that is smaller, and younger (tens of Ma) called glacial-like flows (GLFs). Some 320 of these superposed GLFs (SGLFs) have been found, implying successive glaciation periods. Lobate debris aprons (LDA's) and lineated valley fill (LVF) are now thought to be the same – mostly ice with a covering of debris, their shapes are dependent on their locations. When confined within a valley, LVF is present; in contrast when not confined, this flowing debris covered ice forms LDA's. == More images of glaciers==

Image:Hellas quantangle.JPG|Map of the eastern part of Hellas Planitia (a vast impact crater), showing two large river valleys that slope left, toward the floor of the crater. File:Reull Vallis lineated deposits.jpg|Reull Vallis with lineated floor deposits, as seen by THEMIS. Click on image to see relationship to other features. Image:Niger Vallis hirise.JPG|Niger Vallis with features typical of this latitude, as seen by HiRISE. Chevron pattern results from movement of ice-rich material. Click on image to see chevron pattern and mantle. File:Phlegra Montes in Cebrenia quadrangle.JPG|Material moving down slope in Phlegra Montes, as seen by HiRISE. Movement is probably aided by water/ice. ==See also==