chalk containing clay
41hand tool — any tool or implement designed for manual operation. * * * Introduction any of the implements used by craftsmen in manual operations, such as chopping, chiseling, sawing, filing, or forging. Complementary tools, often needed as auxiliaries to… …
42metalwork — metalworker, n. /met l werrk /, n. objects made of metal. [1840 50; METAL + WORK] * * * Useful and decorative objects fashioned of various metals. The oldest technique is hammering. After с 2500 BC, casting was also used, molten metal being… …
43Chiltern Hills — near Nettlebed Country England Counties Bedfordshire …
44Geology of Hertfordshire — The rocks of the English county of Hertfordshire belong to the great shallow syncline known as the London Basin, the beds dip in a south easterly direction towards the syncline s lowest point roughly under the River Thames. The most important… …
45Anthropology and Archaeology — ▪ 2009 Introduction Anthropology Among the key developments in 2008 in the field of physical anthropology was the discovery by a large interdisciplinary team of Spanish and American scientists in northern Spain of a partial mandible (lower… …
46Sussex — County of Sussex redirects here. For other uses, see Sussex County (disambiguation). This refers to the historic county in England. For other uses either see Sussex (disambiguation) or, for the administrative counties that Sussex is divided into …
47tunnels and underground excavations — ▪ engineering Introduction Great tunnels of the world Great tunnels of the worldhorizontal underground passageway produced by excavation or occasionally by nature s action in dissolving a soluble rock, such as limestone. A vertical opening …
48Concretion — For other uses, see enterolith and nodule (geology). Septaria redirects here. For the genus of gastropods, see Septaria (gastropod). Concretions on Bowling Ball Beach (Mendocino County, California) weather out of steeply tilted Cenozoic mudstone… …
49Ankh-Morpork City Watch — The Ankh Morpork City Watch is a fictional police force within the Discworld series of books by Terry Pratchett. It is based in the city state of Ankh Morpork on the Discworld. The Watch was originally two units, the Day Watch and the Night Watch …
50publishing, history of — Introduction an account of the selection, preparation, and marketing of printed matter from its origins in ancient times to the present. The activity has grown from small beginnings into a vast and complex industry responsible for the… …
