Im no Geologer but heres my understanding of what Pressure Ridges are. When ice layers of different thicknesses crash together (very slowly) resulting in a big messy pile of angular ice blocks. There are two parts to the ridge. One is underwater called the keel and the one on top is called the sail. The driving forces that form the ridges are the currents and winds.
lemarctica 
December 3rd, 2012 at 12:31 am
New York State license plate! That’s a long drive! He he, he he.