The convection cell in the mantle is essentially the self-sustaining, constant movement of the magma inside this layer. This works in a very simple way. The hotter magma is less dense, so it is pushed upward toward the crust above it, while the cooler magma is denser, and it moves downward where it gets hotter, and the process goes on and one. The magma that goes upward toward the crust, manages to push through the thinner and cracked crust between the plates that move away from each other, thus on the divergent plate boundaries. As the magma penetrates through the crust it manages to get to the ocean floor, thus causing volcanic activity. This magma cools of very quickly and creates new crust. Because the magma constantly rises up and creates new crust, the crust piles up and forms an underwater mountain of volcanic origin that constantly has volcanic activity because of the rising magma. This volcanic underwater mountain range is called mid-ocean ridge.
Answer:
Subsidence is so slow that there seems to have been no depression of the upper surface of the lithosphere, so depositional environments are mostly the
same as those in surrounding areas; the succession is just thicker. These
successions are also more complete, however—there are fewer and smaller
diastems—so at times the basin must have remained under water while surrounding areas were emergent. (A diastem is a brief interruption in
sedimentation, with little or no erosion before sedimentation resumes.)
Size, shape: rounded, equidimensional, hundreds of kilometers across
Sediment fill: shallow-water cratonal sediments (carbonates, shales, sandstones),
thicker and more complete than in adjacent areas of the craton but still
relatively thin, hundreds of meters.
Hopefully that helps!
Answer:
- the distribution of earthquakes
- certain fossil distributions
- the distribution of volcanoes
- the location of mountain chains
Explanation:
The plate tectonics are crucial for the processes that happen on the surface or near it on our planet, as well as the physical features of it. The movement of the tectonic plates causes lot of stress when they interact, and from that stress, the crust deep inside cracks and adjusts, which releases a lot of energy and causes earthquakes. Also, on the plate boundaries, because the crust is cracking and is not as tough, the magma from the mantle manages to rise up, and as it reaches the surface it lifts up the land in a cone shape, creating volcanoes, be it as island or continental arcs. When continental tectonic plates collide, they don't subduct, but push against each other, and that enormous pressure lifts up the area around the boundary, gradually giving rise to mountain chains. The fossils are n interesting example as well, as they are one of the best clues about the movement of the tectonic plates. There are lot of fossils that are identical, from the same species, but found on different continents that are not connected in the present, indicating that in the past the continents had different positions and were connected.
