In Europe the Cambrian is very extensively developed, with remarkable differences of thickness in different regions. The maximum thickness occurs on the western side of the continent in Wales and Spain. In Wales are 20,000 feet of conglomerates, sandstones, shales, slates, and volcanic rocks, while in southern Sweden and northwestern Russia the entire period is represented by only 400 feet of beds. Much of the Welsh Cambrian is regarded by Professor Penck as being of continental origin, with occasional incursions of the sea. The Lower Cambrian appears to be limited to the north of Europe, while the Middle Cambrian witnessed the widest transgression of the sea, beds of this date occurring in France, Germany, Bohemia, Spain, and Sardinia. The Middle Cambrian is characterized by the Trilobite genus Paradoxides (Plate III, Fig. 6) which is very common in Europe and in the Atlantic province of North America, but is not found in other parts of the latter continent. The Upper division, like the Lower, is restricted to northern Europe, so that there was extensive submergence in the Middle Cambrian, but a withdrawal of the sea before the beginning of the later portion of the period.

This is in decided contrast to the geographical changes of North America, where the most widespread extension of the sea took place in the Upper Cambrian. In Russia the Cambrian sediments are remarkable for their unconsolidated condition; some of them look as though just abandoned by the sea.

In Norway, 700 N. lat., have been found glacial deposits which are either basal Cambrian or late Algonkian. "The conglomerate in some places is seen to be formed of old moraines. . . . The stones have not the habitus of water-worn rolling stones, but of ice-worn stones. On some of the dolomite ones clear glacial striae were observed. ... At one place plain glacial striae have been found upon the surface of the hard sandstone under a mass of conglomerate." (Reusch).

Cambrian rocks cover great areas in eastern Asia, northern Siberia, Korea, and China. In China these strata, which are but little disturbed, attain the great thickness of 20,000 feet, and consist predominantly of sandstones and limestones. In the lower part are 170 feet of boulder clay of evidently glacial origin. "On the Yangtse River, in 31° lat., i.e. as far south as New Orleans, not high above sea-level, a large body of glacial material was discovered. ... It demonstrates the existence of glacial conditions in a very low latitude in the early Palaeozoic." (Willis).

Cambrian also occurs in northern India, but none has yet been identified in Africa. It is found in the south of Australia and in Tasmania, apparently belonging to all three of the divisions. Evidences of glacial action have been observed in the Australian Cambrian, showing that this climatic change was not local but very widespread, especially as the earliest of the South African ice ages, mentioned under the Algonkian, may have been early Cambrian in date.

In South America, Cambrian has as yet been found only in the northern part of Argentina; it is apparently referable to the Middle division.