Kasei Vallis Erosion (Released 19 April 2005)

Originating on the margin of Lunae Planum, the Kasei Valliscomplex contains two main channels that run east-west across Tempe Terra and empty into Chryse Planitia. <p>The formation of Kasei Vallis is still being studied and several theories exist. It is thought that volcanic subsurfaceing heating in the Tharsis/Lunae Planum region resulted in a release of water, which carved the channels and produced the landforms seen within the channels. One theory is that this was a one-time catastropic event, another theory speculates that several flooding events occurred over a long time period. Others have proposed that some of the landforms (especially scour marks and teardropshaped "islands") are the result of glacial flow rather thanliquid flow. Teardrop shaped islands are common in terrestrial rivers, where the water is eroding material in the channel. A glacial feature called a <a href=&quot;http://www.zephryus.demon.co.uk/geography/resources/glaciers/drum.html&quot;>drumlin</a> has the exact same shape, but is formed by deposition beneath continental glaciers.<p>This VIS image shows a different bank topography thanyesterday's image. In this case, the southern bank is verysteep. There has been erosion and collapse of the steeper bank since the last flow through the channel - note the alluvial fans at the base of the bank cover the smooth appearing channel fill.