Alternate Cold and Warm Periods.—Warm Inter-glacial Periods a Test of Theories.—Reason why their Occurrence has not been hitherto recognised.—Instances of Warm Inter-glacial Periods.—Dranse, Dürnten, Hoxne, Chapelhall, Craiglockhart, Leith Walk, Redhall Quarry, Beith, Crofthead, Kilmaurs, Sweden, Ohio, Cromer, Mundesley, &c., &c.—Cave and River Deposits.—Occurrence of Arctic and Warm Animals in some Beds accounted for.—Mr. Boyd Dawkins’s Objections.—Occurrence of Southern Shells in Glacial Deposits.—Evidence of Warm Inter-glacial Periods from Mineral Borings.—Striated Pavements.—Reason why Inter-glacial Land-surfaces are so rare 236
WARM INTER-GLACIAL PERIODS IN ARCTIC REGIONS.
Cold Periods best marked in Temperate, and Warm Periods in Arctic, Regions.—State of Arctic Regions during Glacial Period.—Effects of Removal of Ice from Arctic Regions.—Ocean-currents; Influence on Arctic Climate.—Reason why Remains of Inter-glacial Period are rare in Arctic Regions.—Remains of Ancient Forests in Banks’s Land, Prince Patrick’s Island, &c.—Opinions of Sir R. Murchison, Captain Osborn, and Professor Haughton.—Tree dug up by Sir E. Belcher in lat. 75° N. 258
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