High Sierra Topix

Thanks, everybody---and sorry I missed you kylekuzma! I was so addled after my inept struggles with elementary forum mechanics that I forgot to post my natural history questions. Here's the main one: What is with the spotted rocks near Porphyry Lake??
What made them that way? Are they some kind of conglomerate? [A geomorphology grad student showed me around Meteora last summer. He was more interested int eh rocks than the monks, which suited me fine. He equipped me with some semblance of a conglomerate concept--something about a glacier's alluvial deposits, composed of silt and the rocks swept up by the glacier. There was a cool epicycle about the size of the rocks in the strata indicating the rate of deglaciation when those strata were deposited.] Why are they distributed in the way that they are? Are these less conspicuously mottled guys (in a creek bed near the confluence of the Triple Peak and the Red Peak forks) kinfolk?

Great trip report, thanks for sharing

Nice trip report. I think I've seen some previous trip reports from you over on Trail Journals (which I haven't visited in quite some time). I know what you are saying about the JMTers. If you meet one and they ask you where your coming from or where you are going and you give them an answer that isn't on the JMT, they look really confused. Explaining to them where it is and that you aren't hiking the JMT doesn't seem to reduce that confusion and occasionally even seems to increase it. I hope to take a couple of weeks to explore Yosemite one day. So many places that I want to go in California and so little time to do it.

I am planning the same loop starting next Friday. The weekly high res on Cal Topo makes the North Side of Red Peak Pass look doable, but I would be grateful for any update. I have the Fernandez/Post Peak passes as a backup plan. I also intend to take the high trail and linger in the Lyell Fork meadow for 2 days. On the way out I will climb up to Clouds Rest and sleep near the Quarter Domes. Half Dome from there then back to the car. Nine or ten nights is the plan as I want to keep days to 7 or 8 miles and spend time reconnecting with mhyself and the mountains.

Since none of our professional geologists on HST have responded about the rocks at Porphyry Lake, I'll take a stab as an amateur geologist (majored in geophysics in college, but then worked in IT my entire career). And yes, I've been there and seen these rocks myself. I've seen similar rocks in several other places in the Sierra, but always on a smaller scale.

What you see are inclusions of older rocks that basically "fell into" the molten granite that was intruding from below. The porphyritic rocks you see now were at the very top of the granite pluton, probably when it stopped moving up and was crystallizing. The older rocks above the pluton are no doubt heavily metamorphosed from the heat of the pluton, and that probably accounts also for their rounded shapes - the corners melt faster.

-Phil

Thanks, wildhiker! (And now I know more about what Porphyry is too!)

Amazing write up! Your info is proving to be very important for my group's attempt at Red Peak Pass on 8/22. Still debating and attempting to find information as the trip nears. Thank you kindly.