of these different rocks
having originally been spread completely around the globe one outside
another like the coats of an onion. With this as a major premise, it is
not surprising that he and his enthusiastic disciples "were as certain
of the origin and sequence of the rocks as if they had been present at
the formation of the earth's crust."[35]

[Footnote 35: A. Geikie, "Founders of Geology," p. 112.]

The amusement with which this onion-coat theory is now regarded is
hardly appropriate in view of its universal vogue among geologists about
the beginning of the nineteenth century, and in view of the further fact
that a very similar and only slightly modified substitute theory has
been universally taught for three-quarters of a century _and still
prevails_. The modern form of the theory substitutes onion-coats of
fossiliferous rocks for onion-coats of mineral and lithological
characters; and a brief consideration of this theory is now in order.

About the time that various geologists here and there were finding rocks
in positions that could not be explained in terms of Werner's theory,
William Smith (1769-1839) in England and the great Baron Cuvier
(1769-1832) in France found characteristic fossils occurring in various
strata; and under their teachings it was not long before the fossils
were considered the best guide in determining the relative sequence of
the rocks. The familiar idea of world-enveloping strata as representing
successive ages was not discarded; but instead of Werner's successive
ages of limestone making, sandstone making, etc., these new
investigators taught that there were successive ages of invertebrates,
fishes, reptiles, and mammals, these creatures having registered their
existence in rocky strata which thus by hypothesis completely encircled
the globe one outside another.

It is true that early in the nineteenth century Sir Charles Lyell and
others tried to disclaim this absurd and unscientific inheritance from
Werner's onion-coats; but modern geology has never yet got rid of its
essential and its chief characteristic idea, for all our text-books
still speak of various successive ages _when only certain types of life
prevailed all over the globe_. Hence it is that Herbert Spencer
caustically remarks: "Though the onion-coat hypothesis is dead, its
spirit is traceable, under a transcendental form, even in the
conclusions of its antagonists."[36] Hence it is that Whewell, in his
"History of the