Geographers would say continents are large, continuous landmasses usually separated by water, while geologists might say continents are ancient, floating slabs of granite rock about 25 miles (40 kilometers) thick. Most people recognize seven continents—Asia, Africa, North America, South America, Antarctica, Europe, and Australia, from largest to smallest—although sometimes Europe and Asia are considered a single continent, Eurasia. Interestingly, all continents except Antarctica are wedge-shaped, wider on top and thinner on bottom, and more than two-thirds of the world's continental area lies north of the Equator.