How come magma deep inside the Earth rises toward the surface?

Question

A. it is denser than surrounding solid rock

B. it is less dense than surrounding solid rock

C. it has the same density as surrounding solid rock

None of those

Answer 1

Well... B, but the answer is a whole lot more complex than that.. it's more like "how does toothpaste come out of the tube when you squeeze it"  it's the same principal at work...  PRESSURE

Answer 2

The pressure argument is generally false, misleading, because the pressure is not unequally applied to a magma chamber as it is when squeezing out toothpaste.  It is simply a matter of buoyancy.  Less dense material tends to rise above more dense material.

Answer 3

B.

As rock inside the earth melts, its mass remains the same while its volume increases--producing a melt that is less dense than the surrounding rock. This lighter magma then rises toward the surface by virtue of its buoyancy. If the density of the magma between the zone of its generation and the surface is less than that of the surrounding and overlying rocks, the magma reaches the surface and erupts.

Answer 4

um.. B. do your own homework.