Question

1. choose the best answer.

in 1928, geologist arthur holmes came up with an idea that the continents were ______.
on plates \floating\ on the mantle
anchored to the earths core by thick, strong columns of solid rock
breaking up into smaller and smaller pieces
stable and interconnected

1. choose the best answer.

the movement of plates of the lithosphere caused by thermal convection is called ______
crustal trek
regional wander
plate tectonics
thermal shift

Explanation:

• For question 8: Arthur Holmes proposed the idea of continental drift where continents are on plates "floating" on the mantle. The other options are incorrect. Anchoring to the core (option 2) is not part of his theory. Continents breaking up (option 3) is not his main idea. And continents being stable (option 4) contradicts the concept of movement.
• For question 9: The movement of lithosphere plates due to thermal convection is called plate tectonics. "Crustal trek" (option 1) and "regional wander" (option 2) are not scientific terms for this. "Thermal shift" (option 4) is also not the correct term.

Answer:

1. on plates "floating" on the mantle
2. plate tectonics