“Oh, Half Dome was cut in half by Glaciers”— WRONG. Read on, my friend!
The rockfalls we are seeing now is exactly how Half Dome was formed. It’s called “exfoliation.”
HD was a dome that rose during the uplift of the Sierra thousands of years ago. It sat with the top at about 9,000 ft. It lay on a joint that runs out towards Cathedral Peak. This weakness, and the process of exfoliation on the north side caused sheets to flake off.
When water got into the cracks it expanded (only fluid to do so) and put pressure on the slabs. When birds pooped and seeds were lodged in cracks, the growth of flora also stressed the cracks. Heat and cold contributed to the granite “stretching.” Domes have energy from when they were magma and are pushing outward.
The glaciers of 15,000 or so years ago lay only up to about 8,300 feet. It was half a dome before the glaciers. The last 700 feet or so was not touched by glaciers. The striations are below that. Yes, the glaciers ate away at the lower levels and carried away the debris.
Unrelated thought worth quoting: “Breathe, breathe in the air. Don’t be afraid to care. Leave but don’t leave me. Look around, choose your own ground.” Pink Floyd
Read “One Best Hike: Yosemite’s Half Dome