How many miles down??
2007-12-16 08:16:12 · 4 answers · asked by sportsgirl5405 1 in Science & Mathematics ➔ Earth Sciences & Geology
It would depend entirely on where you are.
If you are on a thick, old craton it would be 35-50 km.
If you are at a spreading oceanic ridge, it would be 0.
And then anything in between.
2007-12-16 08:21:39 · answer #1 · answered by Lady Geologist 7 · 0⤊ 0⤋
Well, lava is, of course, melted crust likely mixed with stuff from the mantle in some proportion, so zero is a good answer, as far as it goes.
However, if the spirit of your question is how far to the mantle itself, then the answer is different. The thinnest part of the crust is only about 3-4 miles in thickness, beneath where the Moho occurs (the Moho is short for Mohovoricic Discontinuity, the depth at which there is a significant change in seismic waves, probably due to liquid "rock" being present). Beneath the discontinuity is thought to be the mantle, which contains lots of liquid rock (magma). 3-4 miles is minimum, and occurs in the deep ocean basins. Over the continents the depth would be 30-40 miles or so, but it varies, of course, with the terrain; over mountains it would tend to be thicker, and over coastal plains, perhaps thinner.
Recently, by the way, they have discovered what appears to be mantle material (rock, now) at the surface, I believe either in the Caribbean sea or vicinity. They are still trying to determine where that came from, and how it got there.
2007-12-16 16:27:00 · answer #2 · answered by David A 5 · 0⤊ 0⤋
You have to pass through lithosphere .The thickness will be about 20 to 100 k/m.or you can say up to about 65 miles.
2007-12-16 23:58:57 · answer #3 · answered by A.Ganapathy India 7 · 0⤊ 0⤋
Minimum: 0
Just go visit your nearest active volcano.
2007-12-16 16:19:28 · answer #4 · answered by jaz_will 5 · 0⤊ 0⤋