Does grain size determine the porosity of a sediment type?

Why might surface mining be less risky for miners than underground mining? a. surface miners can become trapped in a collapsed mine. b. surface miners work in dusty, enclosed areas. c. surface miners work aboveground. d. surface miners use elevators to enter mines.

Which of the following are causes of coastal erosion? check all that apply. beach grasses and other plants trap windblown sand. wave action carves away the coastline. groundwater under pressure is forced to earth’s surface. artificial structures stop the natural flow of sand along the coast. underground caves collapse as bedrock is dissolved.

And give a detailed description! scientist observes the boundary between two tectonic plates for a decade and finds that no new volcanoes have formed over the course of her investigation. does this result support the theory of plate tectonics? why or why not?