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

What was istanbul called before he ottomans conquered the city in the 15th century

Explain: plate tectonics and people.

Which of the layers of the earth has the following three characteristics? i. it is made of molten rock. ii. it has currents that are constantly moving. iii. earth’s plates float on top of its currents.