94. Name the four great divisions under which the fossiliferous rocks are arranged.
95. Name the Primary or Palæozoic formations. What are the principal kinds of fossils found in the Old Red Sandstone? Which formation is the chief repository of coal in Britain?
96. In what other formations do coals occur? In which formation do the oldest known mammals occur? Name the Secondary formations.
97. Name the Tertiary formations. What kind of climate characterised the northern hemisphere at the beginning of Pleistocene times? What kinds of climate would appear from the evidence to have chiefly prevailed in Primary, Secondary, and Tertiary ages? Have we any trace of frigid conditions during these ages? What is the growing opinion with regard to the climatic conditions during the glacial period of Pleistocene times?
THE END.
Edinburgh: Printed by W. & R. Chambers.
FOOTNOTES:
[A] There are various kinds of felspar; the one referred to above is orthoclase, or potash-felspar.
[B] It is needless to describe the minerals minutely here. The student can only learn to distinguish the different species by carefully examining actual specimens.
[C] Petros, a rock, and logos, a discourse. Some geologists restrict this term to the study of the structure and arrangement of rock-masses, and apply the term lithology (lithos, a stone, and logos, a discourse) to the study of the mineralogical composition of rocks.