Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/46

24 ever content to adopt, years afterwards, a foreign name for a group of strata whose typical completeness lay in their own country. Group 2 is represented as presenting a great variety of mineral structure, which is shown by the comparison of a number of sections. It contains a bed of carbonaceous shale, which, in places, becomes an impure coal. This group, the Professor considers the equivalent of the Roth-todtliegende of Germany. Group 3 is described as being represented on the west coast of England by the thin limestones and shales of the same division, and with them as being the equivalent of the Zechstein of the continent of Europe. Group 4 is described as the equivalent of the St. Bees sandstone on the west (Sections 3 and 4). Prof. Sedgwick places it in its true position below the New Red Sandstone, though possibly he regards it as having more in common with the strata above than with those below. He may not have been far wrong in this supposition, inasmuch as the more complete the sections are that we obtain of groups 4 and 5 the less does the supposed break and unconformity become.

Section 18 is a pit-section at Zwickau, Saxony. It is given in an interesting account of the coal-fields of that country which recently appeared in the 'Colliery Guardian'. Group 2 has, it will be seen, all the characteristics of the same group in the other sections. It may be regarded as typical; for we are told that in many other parts of Germany the coal-formation is immediately overlain by a predominating coarse grey conglomerate. Group 3 has the usual limestones; and group 4 consists, as in the other sections, of sandstones.

Section 19 is a very complete one: it was described by Sir R. I. Murchison as occurring near Semil, in Bohemia. It presents the usual features of groups 2, 3, and 4, with a preponderance, as in the Ifton section, of carbonaceous matter and clays over limestones in group 3.

Section 20 was recently described by Dr. Dawson, of Montreal; and it is perhaps one of the most complete sections hitherto given of the strata under notice.

The section starts, in group 1, with the Spirorbis-limestone, which Dr. Dawson considers the equivalent of that of the English coal- fields. The strata by which this is overlain contain the usual coal- plants with Entomostracan and fish-remains. The uppermost shales abound in Cythere and fish-scales. Group 2 consists of thick grey and reddish sandstones with shales of the same colour, together with thin coals, clays, and nodular limestones: they contain Calamites trunks of Dadoxylon materiarum, Lepidodendron, Pecopteris and Neuropteris. Group 3 is made up of red and grey shales, grey, red and brown sandstones, and a thin coal-seam five inches thick, with