Further reliques of Constance Naden : being Essays and tracts for our times / edited, with an naalytical and critical introduction, and notes, by George MMcCrie . sts of limestones, and there areno greywackes ; while in Kussia there is nothing but lime-stones and blue and red muds. But the three systemsthemselves thin out to the east, so that a thousand feetin Wales is represented by an inch in Scandinavia. Fromthese facts we conclude that the shore of the Proterozoic oceanlay towards the West, where we rind coarse and thick deposits;and that the waters gradually deepened in an easterly direc-
Further reliques of Constance Naden : being Essays and tracts for our times / edited, with an naalytical and critical introduction, and notes, by George MMcCrie . sts of limestones, and there areno greywackes ; while in Kussia there is nothing but lime-stones and blue and red muds. But the three systemsthemselves thin out to the east, so that a thousand feetin Wales is represented by an inch in Scandinavia. Fromthese facts we conclude that the shore of the Proterozoic oceanlay towards the West, where we rind coarse and thick deposits;and that the waters gradually deepened in an easterly direc-tion, becoming clear enough to permit the luxuriant growth ofcorals. The materials carried out come from a continentstretching down the middle of the present Atlantic. Thewhole of Europe was submerged, the deepest parts corre- 24 GEOLOGY OF THE BIRMINGHAM DISTRICT. sponding to those which are now the most elevated. Therocks of all three systems were laid down under conditionssuch as now prevail on the flanks of continents and in deepseas. W Ireland England France Germany ( FT.) () Silu Sweden (20 000 FT.) Norway ! Russia (10,090 FT.) Onl Cam. SKETCH SHOWING GRADUAL EASTWARDLY THINNING OF PR0TER0Z0IC SYSTEMS. Classification:— The whole of the Proterozoic rocks were formerly namedGreyivacke, from their prevailing penological character, orTransition, a term applied by Werner to indicate that theywere physically and biologically intermediate between hisso-called Primary and Secondary systems. Murchison gavethe name Silurian to the two upper divisions of the Grey-wacke, and Sedgwick appropriated Cambrian to the twolower divisions. When, however, the fossils were examined,it was found that the upper member of the Cambrian wasidentical with the lower member of the Silurian. The termCambrian was next restricted to the lowest strata, in whichno fossils had been discovered, and when nearly all of these,a few years later, were found to be crowded with fossils, theywere ad
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