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The long name of "uniformitarianism" is given to Lyell's doctrine, which has exerted an influence upon knowledge far outside the department of geology.
The strongest apparent exception to this latter rule, is that of the so-called "colonies" of M. Barrande, which intrude for a period in the midst of an older formation, and then allow the pre-existing fauna to reappear; but Lyell's explanation, namely, that it is a case of temporary migration from a distinct geographical province, seems to me satisfactory.
Dawson in the carboniferous strata of North America; but now land-shells have been found in the lias. In regard to mammiferous remains, a glance at the historical table published in Lyell's Manual, will bring home the truth, how accidental and rare is their preservation, far better than pages of detail.
Had we space, many more such causes of blanks in our paleontological records might be added. But it is needless here to enumerate them. They are admirably explained and illustrated in Sir Charles Lyell's Principles of Geology. Now, if these minor changes of the Earth's surface produce minor breaks in the series of fossilized remains; must not great changes produce great breaks?
Lyell's discoveries in geology, however, overthrew the argument of the earth's chronology and of the antiquity of man, and Darwin's theory of evolution entirely transformed the accepted beliefs concerning the origin of species and the supposed invariability of animal types. The general superficial resemblance between the fox and many of our dogs, might well excuse the belief in a relationship.
Lyell's conclusion, therefore, is thus far confirmed in the southern hemisphere; and it is the more important, as one is naturally tempted to admit so simple an explanation, that it was the ice-period that caused the extinction of the numerous great mammifers which so lately swarmed over the two Americas.
The fact that no trace of it as been found, it seems to me, invalidates Lyell's theory. Archaean time in geologic history answers to pre-historic time in human history; all is dark and uncertain, though we are probably safe in assuming that there was more strife and turmoil among the earth-building forces than there has ever been since.
At first the full force of these observations did not strike him; for, under sway of Lyell's geological conceptions, he tentatively explained the relative absence of life on one of the Galapagos Islands by suggesting that perhaps no species had been created since that island arose.
These in some cases altered the level of the land, as is related in Lyell's "Principles of Geology." But the effect then was much less than in 1886. Several slight tremors occurred in the early summer of that year, but did not excite much attention. More distinct shocks were felt on August 27th and 28th, but the climax was deferred till the evening of August 31st.
And even the catastrophists, though they met Lyell amicably on almost no other theoretical ground, were inclined to admit the plausibility of his theory of erratics. Indeed, of all Lyell's nonconformist doctrines, this seemed the one most likely to meet with general acceptance.
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