CHAPTER XVII.

FORMER GLACIAL EPOCHS.—REASON OF THE IMPERFECTION OF

GEOLOGICAL RECORDS IN REFERENCE TO THEM.

Two Reasons why so little is known of Glacial Epochs.—Evidence

of Glaciation to be found on Land-surfaces.—Where are all

our ancient Land-surfaces?—The stratified Rocks consist

of a Series of old Sea-bottoms.—Transformation of a

Land-surface into a Sea-bottom obliterates all Traces of

Glaciation.—Why so little remains of the Boulder Clays of

former Glacial Epochs.—Records of the Glacial Epoch are fast

disappearing.—Icebergs do not striate the Sea-bottom.—Mr.

Campbell’s Observations on the Coast of Labrador.—Amount

of Material transported by Icebergs much exaggerated.—Mr.

Packard on the Glacial Phenomena of Labrador.—Boulder Clay

the Product of Land-ice.—Palæontological Evidence.—Paucity of

Life characteristic of a Glacial Period.—Warm Periods better

represented by Organic Remains than cold.—Why the Climate

of the Tertiary Period was supposed to be warmer than the

present.—Mr. James Geikie on the Defects of Palæontological

Evidence.—Conclusion 266

Climate and Time in Their Geological Relations A Theory of Secular Changes of the Earth's Climate · 第 17 / 41 章