Which causes sand dunes to form
a. ocean waves
b. weathering from old rocks in the dessert
c. gravity?

What first caused people to consider that the continents were once one large landmass?

Plzz on what physical process is responsible for the creation of volcanoes, earthquakes and ocean trenches at the plate margins?

The standard deviation of a population is 3.2.what is the margin of error? enter your answer in the box.