Scholars have tried to explain how the Olmecs might have made and moved such big objects. The heads were sculpted out of a hard, dense rock called basalt. Archaeologists think the Olmecs found most of the basalt in the Tuxtlas Mountain range. According to this theory, the basalt heads were sculpted roughly in the mountains and then either floated or dragged by thousands of people from the construction site to the Olmec cities. 