How do the continents move in plate tectonics without being ...

[newyorker26]

How do the continents move in plate tectonics without being broken up by the stresses involved? What will be an ideal response?

Question 2

Consider the table in the chapter listing the various silicate structures of common rock-forming
  minerals. Determine the silicon to oxygen ratio for each type and express it as a decimal fraction. This
  can be done by dividing the number of silicon atoms by the number of oxygen atoms. In the first
  category (isolated tetrahedral), for example, the ratio is 1:4 or 0.25. What can you conclude from this? What will be an ideal response?

[Kimmy]

Answer to Question 1

The continents ride along like passengers on a boat. The boat, in this case, is the underlying upper
mantle or mantle lid, which forms the deeper portions of the lithospheric plate. It is instructive to
keep in mind where the actual plate boundaries are as in the case of South America, for example. The
eastern edge of this plate lies in the middle of the Atlantic Ocean at a considerable distance from the
South American continent. The plate includes not only the land but also the adjacent ocean basin, and
both of these ride like passengers on top of the mantle lid. Also, movement of the plate over the
underlying asthenosphere occurs by flow rather than by mechanical slippage, thus allowing the plate to
move freely without being broken up. As a rule, the breaking up of continents happens as the result of
plate interactions of various kinds

Answer to Question 2

The concentration of silicon relative to oxygen increases as the complexity of the silicate structure
increases. The implication is that minerals with more complex structures will occur in more distilled
(fractionated) magma bodies.

[newyorker26]

Thank you

[Kimmy]

Happy to help you