Barley. Grains remain an important part of the Russian economy.
The answer is the asthenosphere
The continental glacial advanced in the united state was generally from the North to the south.Glacier flow over the land surface along a path of resistance.Alpine glacier into valley causes the glacier to rapidly advance producing a swollen like tongue ice at the glacier snout.
Answer:A. differing densities of the elements that make up the Earth.
Explanation: The densities of the different materials making up the Earth surface and the Earth crust, due to the varying density of these materials it makes it difficult to break certain types of materials.
When the time required to break down materials differ,the earth's surface will have different layers caused by the time difference between the breakdown of these materials.
The more the density of the material the more difficult it is to break it down.
Magmas that are more rich in silica and charged with gas are more explosive
Silica increases the viscosity significantly, but it is not a mineral when it is in the molten state
So silica is the answer