How far down into the ground does el cap go?

Curious about the hull on that thing.

Buzz Hancock wrote:

Curious about the hull on that thing.

Going to dig out a proper sit start?

After some quick Googling I learned that the valley floor has been filled with up to 2000 ft of sand and silt in the time since it was carved by glaciers. So about 2000 ft.

Buzz Hancock wrote:

Curious about the hull on that thing.

I used this as a pickup line once and got slapped

The 2000 foot thing doesn't really work. I don't have an estimate,  much less an answer.  We need a geologist or geomorphologist to chime in on this one.

I don't think El Cap is in danger of falling over. 

The question is somewhat meaningless. El Cap *is* the ground; not just a big rock. 

obviously all the way.

20-30 miles, down to the mantel.  Granite is the prominent constituent of the Earth's crust, so it's safe to say that the granite that makes up El Cap is solid down to the mantel.  

Aaron Kolb wrote:

After some quick Googling I learned that the valley floor has been filled with up to 2000 ft of sand and silt in the time since it was carved by glaciers. So about 2000 ft.

Are you suggesting we've never truly climbed El Cap!?

Does this mean the part under the ground could be even slicker because of the glacier!?

http://npshistory.com/publications/geology/state/ca/cdmg-bul-182/sec4.htm

The base of the Nose is at 4200', so about 1300' down to the valley floor bedrock.

This was an unexpectedly cool question; that's way more sediment than I would have thought.

Sam D wrote:

20-30 miles, down to the mantel.  Granite is the prominent constituent of the Earth's crust, so it's safe to say that the granite that makes up El Cap is solid down to the mantel.  

That makes sense to me. The mantel is where igneous intrusive formations originate, I believe.  Do  you have a background in geo morphology? And feel free to correct me if I am wrong. 

Or do igneous intrusive formations originate in the core? It was a long time ago I took a class in this stuff. CRS, except for a few fancy words I ain't sure about. 

Austin, I do believe the granite of El Cap continues considerably deeper. Granite is molten magma that intrudes into the material above it, until it is far enough away from the core ( heat) to solidify (a pluton of granite). At the edges of the Pluton there will be non granitic rock pieces suspended in the granite ( country rock?) and there will be contact metamorphosis of the surrounding rock caused by the heat of the intruding granite. Something like that anyway. 

Show your work

It seems like there are two different ways of interpreting the question. 1. How far down could one theoretically dig at the base of El Cap before they hit solid granite bedrock that connects El Cap to stuff on the other side of the valley? Looks like Austin found the answer to this one, very cool!

2. How far down does the batholith extend beneath El Cap, and how much taller could it theoretically get if erosion continued through that granite bedrock (I’m guessing the depth of the granite is so large that it would never be the limiting factor to the size of the wall in real life). I don’t think it’s totally obvious that the batholith must extend all the way to the mantle. It seems plausible that the magma plume could have detached from the mantle before solidifying and that the base of the plume could have continued to rise before solidifying (like the wax blobs in a lava lamp), or that it could have sheared off with further tectonic drift after cooling. I’ve never even taken a geology class so that’s all wild speculation; would love to hear the real answer.

Granitic rock is the most common rock type on earth.   The term granite is actually a small subset of granitic rocks that include diorites, monzonites, syenites, etc. But el cap happens to be granite.   Basalt makes up 90% of igneous extrusive rocks, while granite is an igneous intrusive tock. Extrusive rocks harden after they escape the volcano as a flow or as blast debris. Intrusive rocks harden under the volcano and only get revealed via uplift and/or erosion. 

I'm pretty sure the oceanic crust is made of basalt, but the continental crust is made of lighter rocks such as granite.

Many sources say basalt makes up 90% of volcanic rock. But they don’t  say that “volcanic” refers to extrusive igneous rock only. So it can be misconstrued. I’m a geologist, so I know a bit about this stuff. It makes it fun while climbing. I might say something halfway up a climb like, “ Ooh, look at the huge feldspathic phenocryst!”