Petrography lower if wholly or partly vitreous. The specific gravity of the more common rocks range from about 2.5 to 3.2. Archaeologists use petrography to identify mineral components in pottery. This information ties the artifacts to geological areas where the raw materials for the pottery were obtained. In addition to clay, potters often used rock fragments, usually called "temper" or "aplastics", to modify the clay's properties. The geological information obtained from the pottery components provides insight into how potters selected and used local and non-local resources. Archaeologists are able to determine whether pottery found in a particular location was locally produced
What Is History? What Is History? What Is History? is a study that was written by the English historian E. H. Carr. It was first published by Cambridge University Press in 1961. It discusses history, facts, the bias of historians, science, morality, individuals and society, and moral judgements in history. The book was originally part of a series of G. M. Trevelyan lectures given by Carr in 1961 at the University of Cambridge. The lectures were intended as a broad introduction into the subject of the theory of history. Some of Carr's ideas are contentious, particularly his alleged relativism and his rejection of