The S-blade is the most popular form of bulldozer blade, and it is used to push earth. A bulldozer is most recognized for two things: the enormous, heavy steel tracks that replace tires and the big steel blade that is used to push soil, rocks, and trees into large heaps. The term "bulldozer" comes from early machines that worked on farms to level land before planting. These machines had a front end like a truck and a back end like a shovel; they were called "bulldozers" because they leveled the ground like a bull mows down grass. There are several types of blades used with bulldozers including curved blades, scoops, and teeth. Curved blades are attached to the back of the machine and they curve forward over the shoulder of the driver when pushing debris. Scoops are large containers mounted on the end of a dozer blade that can be filled with dirt or some other material. Teeth are small blades attached to the end of the dozer blade that cut through objects such as tree roots. They are useful for cutting through dense vegetation. Dozer blades can get very expensive if you want them to be able to work on different types of surfaces (e.g., soft soil, hard rock). Blades for use in these conditions may have rubber pads on them so they will not damage your driveway or sidewalk. Dozer blades range in price from $10,000 to $100,000 or more.