This photo pair shows two views of an alpine lake above Costello Creek in the Broad Pass area. This area was inundated by glacial ice 20,000 years ago, which scoured out the pattern of ridges and depressions that you see in the photos. Once the ice sheets melted, water filled the depressions to form the ponds present on the landscape today. Current vegetation in the area is low alpine tundra dominated by heath family plants and mountain avens on the knobs and wet sedge-dominated communities in the low areas ringing the ponds.