yosemite/hetchhetchy

“planning on packing from dam
to rancheria falls on may 18
any suggestions?”

“I suggest you have fun!”

“Yeah, drop a few sticks of dinamite at the base of the dam. LOL :)”

“I'm with ThinAir. By the way, my city just put a bust of O'Shaughnessy--the guy who murdered Hetch Hetchy--in City Hall. :-p”

“Anyone want to hear some interesting Geology about Yosemite?”

“yes”

“Well...ummmmmm....ah...actually I was thinking of Yellowstone! But I do know something about Yosemite's geology.

As far as glacial geology, Yosemite is one of the best North American examples of an alpine glacier-carved valley, wide trough sloping steeply to towering vertical cliffs, polished and striated bedrock. The major glacier of that valley scoured the granite walls such that it left all tributary stream valleys "hanging", subsequenlty creating the many waterfalls of this park. It's amazing what a glacier can accomplish...with time.”

“Thank you, how about Yellowstone?”

“Yellowstone has a buttload of geologic topics that can be discussed. The one I had in mind is why the hotsprings exist.

Yellowstone sits atop a huge cauldera, a hotspot underneath a very thin portion of the earth's crust. It's this proximity of the groundwater with the intense heat that causes the occurrance of the hotsprings.

But the scary thing about the hotspot is the fact that the land surface above this area has collapsed into the underlying magma chamber at least 2 times in the past.

Try to compare this regional area to the small area of a volcano. The forceful injection of magma within tubes in a volcano, then the volcano eruption...now visualize an area of tens of square miles literally falling into the earth, and the eruption that that event would cause.

As pressure increases, the magma chamber rises causing the land surface to also rise. Circular "ring" fractures form around the region. This fracturing causes the land surface to violently collapse into the chamber. THEN, intense pressure is released expelling gasses, and ejecting thousands of square kilometers worth of red-hot pumice, ash and dust

Magma is alot more than molten material, it has a buttload of compressed gasses in it. When it reaches the earth's surface to standard T & P, the gasses expand, much like when a soda can is opened, at an explosive rate. You saw what Mt. St Helens did when it blew. Well, the size of the Yellowstone cauldera makes conditions ripe for an explosion that only equal to a large-scale meteor impact.

Will Yellowstone ever experience another cauldera collapse? It is not a matter of if...it is a matter of when! I just hope I'm not around to experience it and its affects.”

“THAT is interesting information. When did the last one happen? I don't want to be around either. Are you a geologist or did you stay at a Holiday Inn Express last night?”

“lol”

“The bears at Rancheira Falls are notoriously crafty. I've got a picture of one of 'em pulling a bear bag out of a tree. The same bear the next morning was digging through our packs. Nothing like a little, well actually a lot of bear slobber all over everything.

The interesting thing was that the packs were leaning up against a rock right next to a friends tent. The bear was literally hovering over my friends head while getting into the packs. Fortunately the roar of the waterfall and creek were so loud that he didn't hear the bear above him.

One other thing, prepare to get wet while walking along Hetch Hetchy, one of the waterfalls crashes onto the rocks and gets everything nearby soaked in early season including the trail and those that hike it.

Enjoy your trip, it's a beautiful area and makes for a great early season trip. Oh, and watch out for the bats in the tunnel.”