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Cambrian, a. (n.)|ˈkæmbrɪən|
[f. Cambria, var. of Cumbria, latinized derivative of Cymry (: —OCeltic Combroges ‘compatriots’) Welshmen, or of Cymru Wales. Cumbria and Cambria were originally the same, but were subsequently differentiated: Cambria was regularly applied to Wales by Geoffrey of Monmouth. (Some think that Cymru, a late word, is only a variant of Cymry the name of the people, parallel to the later Eng. use of Wales = OE. Wealas ‘Welshmen’, as the name of their country.)]
1. Pertaining to Wales, Welsh; n. a Welshman.
[1586J. Hooker Girald. Irel. in Holinshed II. 24/2 There came vnto him a Welsh or a Camber woman. 1626W. Sclater Expos. 2 Thess. (1629) 299 Wee, Brittans of t'other race, are growne all Cumber, Camber; quite changed from the temper of our peaceable forefathers. Cf. kim kam, cam a.] 1656Blount Glossogr., Cambrian, Welch, Brittish. 1780Von Troil Iceland 211 Among the ancient Cambrians. 1860All Y. Round No. 68. 420 Change is too strong even for Cambrian nationality.
2. Geol. A name given by Sedgwick in 1836 to a group or ‘system’ of Palæozoic rocks lying below the Silurian, in Wales and Cumbria.
As originally defined, the Silurian of Murchison and Cambrian of Sedgwick, being established in different districts, were found on further investigation to overlap each other; the Cambrian is now generally held to include the Tremadoc slates, Lingula flags, Menevian beds, and Longmynd group, containing the Harlech grits and Llanberis slates; but the Geological Surveyors limit the term to the Longmynd group, while others extend it to include all the Lower Silurian of Murchison (Bala and Llandeilo groups).
1842H. Miller O.R. Sandst. xii. (ed. 2) 257 The geologist has learnt from Murchison to distinguish the rocks of these two periods,—the lower as those of the Cambrian, the upper as those of the Silurian. 1873Geikie Gt. Ice Age xvi. 207 In Lewis we get boulders of Cambrian sandstone. 1876Page Adv. Text-bk. Geol. xi. 193 The Cambrian may vary in composition in different regions.
▸ Cambrian explosion n. Palaeontol. a short episode of intense diversification of marine animal forms apparent from the fossil record of the Cambrian period (including the development of mineralized skeletons in many groups and the appearance of ancestral forms of most modern metazoan phyla) which is dated to about 535 to 525 million years ago; also fig.
[1964L. V. Berkner & L. C. Marshall in P. Brancazio & A. Cameron Origin & Evol. Atmospheres & Oceans vi. 117 No advanced precursors to the Cambrian evolutionary explosion should be expected until oxygenic levels presaged the opening of the Cambrian.] 1977S. J. Gould et al. in Paleobiology 3 25/2 The actual history of life included a preequilibrial phase of rapidly rising diversity; it is called the *Cambrian ‘explosion’. 1995Nature 26 Oct. 682/1 The Cambrian Explosion occurred in a geological moment, and we have reason to believe that all major anatomical designs may have made their evolutionary appearance at that time. 2002Internat. Rev. Law & Econ. (Nexis) 22 As information production has become more central to our economy, we have seen a ‘Cambrian explosion’ of exclusive private rights in information. |