Split Rock: An Investigation Virtual Cache
Split Rock: An Investigation
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This is a marvelous opportunity to see a large boulder close up just after it has had a major slab split from it.
"Sometimes rocks weather by peeling off in sheets rather than eroding grain by grain. Exfoliation is scientific Latin for that process. It can happen in paper-thin layers on individual boulders, or it can take place in thick slabs as it does here, in Yosemite Valley, California."
"The great white granite domes and cliffs of the High Sierra, like Half Dome, owe their appearance to this type of exfoliation. These rocks were emplaced as molten bodies, or plutons, deep underground, raising the Sierra Nevada range. Erosion then unroofed the plutonic rocks and took away the pressure of the overlying rock. As a result, the solid rock acquired fine cracks through pressure-release jointing. The combined work of gravity, weathering, plant roots, and the expansion of freezing water opened up the joints further and loosened these slabs."
Half Dome also had to deal with glaciation. But what happened here? It appears that this slab split from its boulder was accelerated by the sheer impact of this huge boulder with the ground. This slab may have separated upon impact, or it may have separated years later, having been weakened by the initial impact.
It's not often that many of us get to see a rock in this position so close to its initial split. It's amazing to me that more hikers on the nearby trail don't stop in wonder and explore this amazing exhibit of nature.
How did this rock split? Do you know the answer? Do you have more information to add to this analysis? Let me know and I will update this geocache web page.
TO GET CREDIT FOR THIS CACHE, email to me answers to the following questions:
1. Standing at the coordinates and facing the split rock boulder, is the smaller portion of the split to your left or your right?
2. Standing in that same position, there is a posted sign to your left. How many trunks does the tree behind it have?
Please do not log the answers but send them to me via email and go ahead and log your cache. As always, you can email cache owners through the owner's profile above.
A SPECIAL CONGRATULATIONS: A special congratulations to Right Turn Only for finding that there is a benchmark on the Split Rock.
Additional Hints
(Decrypt)
Yvsg hc gur obhyqre naq frr jung'f haqre vg.