GRAND DISCOVERIES OF LIFE 
3 
notable discoveries, half a century before, of the Siluria and 
Cambria in England. 
In this connection the crystalline complex of the Piedmont 
Plateau, in Maryland, where our zoologist was homed, was under 
especial surveillance. It was fondly expected that some of these 
rocks which had always been considered as among the very oldest 
parts of the Archean massif, if not actually a section of the 
primeval crust, might prove to belong to the so-called Algonkian 
sedimental column. At this very time under the aegis of the Johns 
Hopkins University, at Baltimore, these crystalline schists were 
subject of intensive study. Some of the results published started 
wide and warm discussion through the world. 
With this astounding setting before him, that at the beginning 
of Cambric time biotic types were already so widely and funda¬ 
mentally differentiated, and the further anticipation of great 
extension of the life record into time before Cambric, the nature 
of the pre-Cambrian life at once attracted the attention of Prof. 
W. K. Brooks, foremost zoologist and evolutionist of his day. 
Gathering from the geologists on the Piedmont Plateau, what he 
could concerning the physical setting of pre-Cambrian sedimenta¬ 
tion, and the character of the earliest Cambric faunas, he began 
to speculate from the zoologists’ viewpoint upon the aspects of 
life in these early times. His meditations crystallized into that 
masterly essay on the origin of the oldest fossils and the evolu¬ 
tionary significance of life’s discovery of the bottom of the sea. 
A supporting companion memoir by one of the Hopkins geolog¬ 
ists, on the pre-Cambrian rock-section, was originally intended to 
go with the Brooks’ essay. This, however, by curious decree of 
the Fates never materialized. The Piedmont Plateau schists 
turned out not to be Algonkian at all, nor even pre-Cambrian in 
age. They were found to be only highly metamorphosed repre¬ 
sentatives of the same Paleozoic strata, of Cambric, Ordovicic, and 
Siluric ages, that were exposed unaltered farther west in the 
Appalachian Mountains. 
The lowering of the life record into the abyss of time was not 
yet a reality, but, as it eventually proved, was a distant accomplish¬ 
ment a quarter of a century later. A vast pile of pre-Cambrian 
sedimentaries resolved itself in the Lake Superior region and in 
the Canadian Rockies. Instead of a single such system, as had 
been fancied, two great eral rock successions developed, each com- 
