A Manual of Elementary Geology or, The Ancient Changes of the Earth and its Inhabitants as Illustrated by Geological Monuments

CHAPTER XXVII.

Chapter 3065 wordsPublic domain

SILURIAN GROUP.

Silurian strata formerly called transition--Term grauwacke--Subdivisions of Upper and Lower Silurian--Ludlow formation and fossils--Wenlock formation, corals and shells--Caradoc and Llandeilo beds--Graptolites--Lingula--Trilobites--Cystideae--Vast thickness of Silurian strata in North Wales--Unconformability of Caradoc sandstone--Silurian strata of the United States--Amount of specific agreement of fossils with those of Europe--Great number of brachiopods--Deep-sea origin of Silurian strata--Absence of fluviatile formations--Mineral character of the most ancient fossiliferous rocks 350