Earthworks are engineering works created through the moving of massive quantities of soil or unformed rock. Engineers need to concern themselves with issues of geotechnical engineering (such as soil fluidity and friction) and with quantity estimation to ensure that soil volumes in the cuts match those of the fills, while minimizing the distance of movement. In the past, such calculations were done by hand using a slide rule and with methods such as Simpson's rule; now they can be performed simply with a computer and specialized software. Due to the massive amounts of material to be moved — millions of cubic yards in the case of large dams — earthwork engineering was revolutionised by the development of the (Fresno) scraper and other earth-moving machines such as the loader, production trucks, the grader, the bulldozer, the backhoe and the dragline excavator. Typical earthworks include roads, dams, dikes, canal, bunding and berms ("noise mounds"). In military engineering, earthworks are, more specifically, types of fortifications constructed from soil. Although soil is not very strong, it is cheap enough that huge quantities can be used, generating formidable structures. Examples of older earthwork fortifications include moats, sod walls, motte-and-bailey castles and hill forts. Modern examples include trenches and berms.
