e continents would
have been all washed away long ago."

"Yes, there have been, since geological history began, at least twenty
whole mountain ranges as high as the Rockies worn to sea level. Of course
the oceans have periodically flooded the margins of the continents at
such times, in long troughs where now stand our Appalachian and Rocky
Mountain ranges, leaving their deposits.

"In the Rockies there are coarse sediments miles deep, together with
limestone formed of the ground-up shells of marine animals of the earlier
times. Now think of this!

"If all that stands above sea level in the United States to-day were to
be washed into the sea, as it undoubtedly will be, in time,--(but not in
our time), the level of the oceans will rise, (just as the level of a
half glass of water rises if you drop in a handful of sand), until--it
has been estimated--everything under six hundred and fifty feet above sea
level will be inundated. That means that probably half of the continent
would be under water. It has been so in times past, and it will be again.
In fact, in the age of reptile dominance, (the Cretaceous Period), when
the earth was just beginning to be peopled with birds and flying
reptiles, and the first, primitive mammals,--the Atlantic flowed straight
from what is now the Gulf of Mexico, through what is now the Rocky
Mountain Region, and through the Eastern part of Alaska, to the Arctic.
That left one strip of land that reached along what is now the Pacific
Coast, clear from the Isthmus of Panama to the Aleutian Islands and
straight across to Siberia. The Northern part of the Atlantic Coast
formed another land area, broken by the fresh water bodies of America and
Canada and in one with a strip of land that extended across Greenland to
Europe.

"It is pretty well established, in fact, that the United States has been
more or less flooded by warm, shallow marine waters at least sixteen
times since the age of fish dominance began. But not since the age of
man!" he hastened to assure the old prospector, who was beginning to look
uneasy.

"Of course these flood times brought a moist, warm climate to the land
areas, and life was easy for the then existing animal forms. Then when
readjustments in the earth's crust again raised up mountain ranges and
the climate became colder and drier, the struggle for existence became
more intense, the process of evolution was stimulated, and new forms
originated.

"We are living in one