. Elements of geology. Geology. PART 11. CHAPTER XV. 195 Chalk Needles Cretaceous Group. away the stone, as well as to throw up a beach at the same level.* The needles of the Isle of Wight, and the Old Harry Rocks of the coast of Dorsetshire, are well known to those who have examined the chalk cliffs of the South of England. Besides the inland columns in Normandy, above described, there are others more recently formed on the sea coast of that same country. Fig. JVeedle and Arch of Etretat, in the chalk cliffs of JVonnandy, Height of Arch 100 feet. (Passy.)t If we inquire at what period t
. Elements of geology. Geology. PART 11. CHAPTER XV. 195 Chalk Needles Cretaceous Group. away the stone, as well as to throw up a beach at the same level.* The needles of the Isle of Wight, and the Old Harry Rocks of the coast of Dorsetshire, are well known to those who have examined the chalk cliffs of the South of England. Besides the inland columns in Normandy, above described, there are others more recently formed on the sea coast of that same country. Fig. JVeedle and Arch of Etretat, in the chalk cliffs of JVonnandy, Height of Arch 100 feet. (Passy.)t If we inquire at what period the emergence and denudation of the cretaceous rocks took place, we shall find that it occurred in great part after the deposition of various marine tertiary forma- tions, so that both the cretaceous and tertiary beds were upraised together. The greatest elevation which the chalk reaches in England, is the summit of Inkpen Beacon, in Berkshire, which is 1011 feet above the sea; but marine deposits of the same age attain an elevation of 8000 feet in the Alps and Pyrenees. These may have partly emerged during the cretaceous period, just as the coral reefs in some regions of the Pacific are grow- ing in one spot, while other portions of the same have been uplifted by subterranean forces, and converted into land. Difference between the chalk of the north and south of Europe.—By the aid of the three tests of relative age, namely, superposition, mineral character, and fossils, the geologist has been enabled to refer to the same cretaceous period certain rocks in the north and south of Europe, which differ greatly both in their fossil contents, and in their mineral composition and struc- ture. If we attempt to trace the cretaceous deposits from England * Captain Bayfield, Geol. Trans., Second Series, vol. v. p. 94. Also Principles • of Geology, Index, " Niapisca ; t Seirie-Inferieurc, j). 142. and plate 6. fig. Please note that these images are extracted from s
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