Hi polar<br /><br />Good to see you are still working on it.<br /><br />With respect to U shaped valleys, you first need to demonstrate that linear filles have U-shaped profiles. If they do you then have to show they have other features associated with glaical erosion and deposition. If formed by valley glaciers they should cirques at one end and terminal moraines at the other. <br /><br />With respect to large boulders, these can be formed by a range of processes, such as impact ejecta. We know that the lunar surface has many impacts and so large boulders are to be expected. To determine whether a particular boluder is an eratic you need to look at its association. The Apollo 17 site was well studied and is well documented. Jack Schmitt, the only geologist who went to the moon was LM pilot on Apollo 17. He worked for several years in Alaska and Norway and so would be very familiar with galcial erosion and deposition and would have recongised glical features had they been present. None were reported.<br /><br />With respect to polar accretion of ice and short lived ice sheets I think it is important to distinguish between the presence of ice, which is a possibility on the moon, and glaciers. A glacier is not simply ice, it is a dynamic ice system that has undergone flow. The presence of ice, per se, does not mean you have a glacier. Ice can be present as ground ice, frost, snow without forming glaciers. Therefore to demonstrate glaciers you have to demonstrate flow. Hence the importance of evidence glacial erosion and deposition in the case of former ice. <br /><br />Just thinking about lunar glaciers generally, to get ice to flow you need pressure. On earth about 60 m of ice is needed before it with flow as a glacier. Under lunar gravity you would need a lot more - I would guess six times, say 360 m. this is a lot of ice. Secondly you would need a source of ice. Any ice exposed to lunar sunlight with sublime very rapidly, that is why the polar ice, if prese <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em> Arthur Clarke</p> </div>