CAMBRIAN SYSTEM. 70 CAMBKIDGE. places, liit in otlicr localities, where ilitTcrciit members of the formation are exposed, life re- mains abound, showing a profusion of marine invertebrates and plants of low order. The animal remains inehule, in order of their im- portance, crustaceans, bracliiopods. pteropnds. worms, <;astro]iods. hydrozoans. ccliinodcrnis, sponges, corals, lamdlibranchs, and ceplialopuds. All of these, except the i'e|)halopods, were repre- sented in the earliest periods of the Cambrian system . While the great thickness of Cand)rian strata indicates a long period of sedimentation, still the great changes that we tind in the faunas in passing from one division of the Cambrian sys- tem into another are considered remarkable, since they indicate a most complete revolution in the life torms in any one region. Thus, of the many trilobites found in the Lower Cambrian, but few are known in the middle division: and these, in turn, dift'er markedly from those in the Upper Cambrian. The reason for this absence of transitional ty])es may be due to the fact that the intermediate beds containing them have not yet been discovered. The trilobites were a prominent feature of the Candirian system, and varied nuicli in size, from under an inch, like the small, blind ones, agnostus, to others having a length of two feet, as paradoxides. Xo Verte- brate remains have been found. There is no evidence of invertebrate life that existed on land in fresh water, although it is quite pos- sible that some of the mollusks found may have lived in estuaries of brackish water, for the character of many of the sedimentary rocks of Cambrian time, such as grits, with ripple-marks, is indicative of shallow-water cmiditions. The thickness of the Cambrian system is variable. In Newfoundland it is about 0000 feet; in Vermont and eastern New York, 7000 feet; in British Columbia. 10,000 feet. The Cambrian rocks include sandstones, limestones, shales, slates, marliles, and quartzites, with oc- casional igneous rocks, as in the Lake Superior region and soiitheastern Pennsylvania, and also in Great Britain. The metamorphosed Cambrian rocks are found in areas of much folded strata. In America the Cambrian rocks have been classi- fied under: (1) Georgian series, or Lower Cam- brian, a local development in Michigan being known as the Kcifcciuiiriiii. or Ketvcviiinx : in this the triloI)ite olenellus is often connnon. (2) Acadian, or ^fiddle Cambrian, in which the tribolite paradoxides is abundant in places. (3) Potsdam, or L'pper Cambrian. In North America Candjrian rocks are fomid in Newfoundland, Nova Scotia, New Brunswick, and Canada: also in Vermont, Massachusetts, Maine, New Hampshire, Rhotfe Island. New York, New Jersey, Pennsylvania, JIaryland, Tennessee, Alabama, Georgia, Michigan, Wis- consin, North Dakota, California. Colorado, Arizona. In foreign countries, they are known in Great Britain, (jermany, Bohemia, Scandi- navia, Krancc. S])ain. Sardinia. China. Australia, and India. The British, Bohemian, and Scandi- navian areas are of classic interest. The eco- nomic products of the Cambrian .system in the L'nited States include the slates (q.v.) and linionite ore (q.v.) of the Appalachian States, sandstone in New York, and cojiper ores in Michigan. Consult: W'alcott, Tenth Annual Report I iiited Slatex tleological Survey (Washington, 1888) ; Biillelin SI. Vniled Stales fleoiotjieal Surrey (Washington. l.'^Ol); Dana, Manual of Geology (New York. 18!t")) ; Geikie. Text-hook of Geology (London, 1893). See Geology; Potsdam Sandstone. CAMBRIC, kiimlirik. A general term ap- plied to the linest and tliinuest of linen falirics. It is said to be derived fr<mi Cambrai (France), where such goods were first made. Some of the linest cambrics of the ])reseut day are produced in Switzerland. Scotch cambric is really a nuislin, and is made of cotton with the fibre twisted very hard, to imitate real or linen cam- bric. CAMBRIDGE, kam'brij (Cam bridge; Neo- l^at. t'lintahriiiin) . The county-town of Cam- bridgeshire, England, situated on the Cam, about 57 miles north-n(nlheast of London (ilaj): Eng- land, G 4). The town, as a whole, is less ]iic- turesque than its rival, Oxford, and its main street, Trumpington, docs not compare favor- ably with the famous High Street of Oxford. On the other hand, many of its college build- ings are, from an architectural standpoint, the equal of any which its sister university pos- sesses; and the beautiful lawns and gardens behind the colleges, traversed by the Cam. fa- miliarly known as 'the Backs.' certainly equal in beauty the justly praised Clirist Church Meadow of Oxford. Apart from the colleges and the buildings immediately connected with them, Cambridge possesses few interesting features. The Church of the Holy Sepulchre is worthy of note as being one of the four existing round cliurclies in England. Cambridge is a Parliamen- tary borough, and sends one member to the Mouse of Commons. The city maintains a large public library and makes large grants to a iiiiin- ber of schools. Its water, gas. and electric-light plants are in the hands of jirivate companies. Its drainage and .sewerage system has lieen re- cently improved. Population, in 1801, 37.000; in l'.)01, 38.400. Cambridge, probably on the site of the Vamhuritum of the Romans, takes its name from the river Cam, which was anciently, and is still in its upper reach, called the Granta. To the Saxons. Cambridge ajqiears to have been known as Grantabrydge. In 870 the Danes rav- aged the country hercabiiuts. and arc said to have destroyed the town. William the Conqueror built a castle here, and the town received its first charter from Henry I, in 1118. King .John, in 1'200, granted a charter to the town, ]ieriiiitling it to have a guild of merchants, and in 1207 confirmed the burgesses in their privileges in perpetuity. See Cammkidgk, Umvkksity or. BiRi.looHAl'llY. Atkinson, Camhridge Dcserihed and llluslraltd (London. 18!t7) ; Humpliry. fV/»i- hridge (Cambridge, 1880); Maitland, Cainhridge Tounship and liorough (Cambridge. 18!18) ; Wood. "Cambridge in Early and Mediseval Times," in liuilder. Vol. LXXXI. (London, 11)01). CAMBRIDGE. A village and county-seat of Henry County. 111., 30 miles smitheast of Kock Island, on the Rock Island and Peoria Railroad (Map: Illinois, B 2). it is the centre of a fer- tile agricultural region, and exports live slock and grain. I'opulation, in 1890, 040; in 1000, 1345.
