24 
AMERICA THE OLD WORLD. 
Upper Mississippi, and immediately along its base 
are gathered the Azoic deposits, the first strati- 
fied beds, in which the absence of life need not 
surprise us, since they were formed beneath a 
heated ocean. As well might we expect to find 
the remains of fish or shells or crabs at the bot- 
tom of geysers or of boiling springs, as on those 
early shores bathed by an ocean of which the 
heat must have been so intense. Although, from 
the condition in which we find it, this first granite 
range has evidently never been disturbed by any 
violent convulsion since its first upheaval, yet 
there has been a gradual rising of that part of 
the continent, for the Azom beds do not lie hori- 
zontally along the base of the Laurentian Hills 
in the position in which they must originally 
have been deposited, but are lifted and rest 
against their slopes. They have been more or 
less dislocated in this process, and are greatly 
metamorphized by the intense heat to which they 
must have been exposed. Indeed, all the oldest 
stratified rocks have been baked by the prolonged 
action of heat. 
It may be asked how the materials for those 
first stratified deposits were provided. In later 
rimes, when an abundant and various soil covered 
Che earth, when every river brought down to the 
ocean, not only its yearly tribute of mud or clay 
or lime, but the debris of animals and plants that 
