324 
I'he Amerlc((}l GeoUxjixl . November, 1896 
marks in regard to the first, (geologi(;al time) are very apt, and we quote 
them to give an idea of the writer's style. The ordinary ideas of time 
c-annot be appHed in geology because they so far exceed all ordinary 
modes of measurement. Geology deals with such vast time epochs that 
for all practical purposes time is infinite. "Science, especially the sci- 
ence of geology, dispenses time as th(^ commonest drug in the market of 
the universe." 
"The idea of precise time is the product of the routine of civilized 
human existence. It is unknown in the vegetable and animal worlds; 
it is disregarded by nomadic races. The idea took root when the home 
was organized by women and meals were cooked at fixed hours of the 
day. It became confirmed when superstition organized priestcraft, and 
religious ceremonies demanded a calendar. The moon was the first 
clock. . . . Even now, with all the chnmometers of Christendom, 
it is still a fact that nineteen-twentieths of the human race have never 
seen a clock, and have no practical need of one." (p. 7.) 
Several examples are given of the methods of estimating geological 
time, as from the rate of deposit or the rate of erosion. He does not be- 
lieve, howevfT, in the elaborate methods adopted by some to estimate 
the age of the earth, although erosion can be used as a rough means of 
estimation. So that basing the rate of erosion in the Juniata valley at 
one foot in 1,500 years, and calculating the average elevation of the 
country originally at 9,000 feet, some 1.3.560,000 years would have to 
elapse to bring the country to its present level. 
Prof. Lesley is not a believer in the theory of the permanence of 
continents and oceanic basins, remarking (p. 37): "The two thoughts 
which are here fundamental to the knowledge of our Pennsylvanian ge- 
ology are these: (1) that what was the continental area of crystalline 
rocks became by the downward movements of the earth's crust an Appa- 
lachian sea basin of unknown depth, and was in the course of the Cam- 
brian, Silurian, Devonian and Carboniferons ages so completely filled 
ujj as to become at best a great marsh or archipelago of marshes, bear- 
ing the vegetation of the coal; and (2) that this whole area was then 
lifted high into the air; that a corresponding contemporaneous move- 
ment established the Atlantic ocean or parts of it, as the thrust which 
elevated the Appalachians came from that direction: and that submer- 
gence of other lands of the world must have been occasioned by the 
general rise of the .sea level." 
Dr. Walcott has expressed his belief that the sediments of the Lower 
Cambrian were deposited in troughs extending northeast and south- 
west along a continental mass lying to the westward: but Prof. Lesley 
believes the sediments of the whole Paleozic period, from the Cambrian 
to the Carboniferous were derived from a continental mass lying to the 
eastward, and that when the Mesozoic began "a genuine cataclysm" 
produced the continental area of the United States. For he says: "The 
overthrust faults are of themselves alone sufficient to prove it. A belt 
of parallel mountains, as high as any that now exist in South America 
or Asia, rose into the air along a line extending from the St. Lawrenco 
