Chapter XIII

GEOLOGICAL CHRONOLOGY--REMARKS ON THE SUCCESSION OF
ORGANIC LIFE.

Summary of the History of Stratified Rocks--Striking Characteristics
of certain Formations--Human Remains found only in
superficial Deposits--Gradual Transition from the Organic Life
of one Period to that of the next--Evidence in favor of this
Opinion--Advance from Lower to Higher Types of Organic
Life as we ascend from the Older to the more Recent Formations
--Economic Value of Geological Chronology--Illustration--Search
for Coal--the Practical Man at Fault--the Geologist
comes to his aid, and saves him from useless Expense, 217

CHAPTER XIV.

SUBTERRANEAN HEAT--ITS EXISTENCE DEMONSTRATED BY FACTS.

Theory of Stratified Rocks supposes Disturbances of the Earth’s
Crust--These Disturbances ascribed by Geologists to the Action
of subterranean Heat--The Existence of Subterranean Heat,
and its Power to move the Crust of the Earth, proved by direct
Evidence--Supposed Igneous Origin of our Globe--Remarkable
Increase of Temperature as we descend into the Earth’s Crust--Hot
Springs--Artesian Wells--Steam issuing from Crevices
in the Earth--The Geysers of Iceland--A Glimpse of the subterranean
Fires--Mount Vesuvius in 1779--Vast Extent of
Volcanic Action--Existence of subterranean Heat an established
fact, 233