http://everyjack.com/2015/05/17/75/ Across from camp, seven triangular ridges expose layers of granites and metasediments, sandwiched between steep tributary icefalls. Reaching the cliffs requires crossing the five-mile-wide Darwin Glacier. Although the Darwin has a central corridor of shiny sun-scoured blue ice, strips of crevasses line the edges. Melt water runs in and amongst crevasses, creating mazes of small channels and deep cracks. Complicating navigation, variable amounts of wind-blown snow cover and hide the surface of the glacier. Fortunately, we have been joined by Alaska Larry, a mountaineering guide on Denali in the other summer, to help navigate the Darwin.
After an hour of zig-zagging between crevasses on snowmobiles, we reached a tumultuous region where the ice falls merge with the blue wavy ice of the Darwin. Larry dismounted every several yards to poke and probe the ice, but I kept my ice axe convenient in case I needed to make a hasty jump off a tumbling snowmobile. I can testify that the machines have an impressive ability to bridge crevasses up to two feet wide (if on a perpendicular trajectory of the crack) and we eventually made it through a hazardous rollercoaster course to the cliffs. Cramponing up a steep snow chute provided great access to several prominent granite layers that we sampled while hiding from occasional loose rocks crumbling from the cliffs above, thawed by the afternoon sun.