THE SCIENTIFIC MONTHLY. ' 563 
?, « 4. <■ ■^VIEWSAND LITERARY NOTICES. 
* Climate'and Time in their Geological Relations. —A theory of secular 
changes of the earth’s climate; by James Crall/of Her Majesty’s Geological 
Survey of Scotland. D. Appleton & Co., N. Y. 
Scattered all oyer our country, from the higher latitudes to the 40 th parallel, 
are huge erratic blocks of massive grantite. These appear on the surface and all 
through the drift. They were transported from the North—from the Azoic axis — 
to the regions where they now repose. We know that the erratic foreigners were 
transported from northern regions, ( 1 ,) because they are not indigeneous, ( 2 ,) 
because enormous bluffs of granite rock—such, for instance, as Huronian Hills 
and Laurentian Mountains—are exposed in these regions and nowhere else; and 
( 3 ,) because these granite erratics have been traced by scientific men to these 
Azoic regions. 
Besides these boulders there are innumerable scratchings, ploughings, and 
groovings, traversing our country in systems; the scratches and grooves of any 
given system are always parallel. Systems sometimes cross each other, producing 
a confusion of scratchings and groovings. And the surface of the rocks are 
frequently planed perfectly smooth. 
The question respecting the power which transported these boulders and 
planed, grooved,-and striated the rocks, (it has been the unquestioned belief of all 
persons qualified for an enlightened opinion upon the subject, that the presence of 
both these phenomena are owing to the same great cause) has ever been a much 
vexed, and is still an unsettled one. It has been suggested that these erratic 
boulders were swept down from higher latitudes by the impetuosity of a mad tor¬ 
rent; and that the transportation of these immense masses of rock in this manner 
produced the planings and groovings mentioned. It being difficult to conceive 
of a torrent of sufficient force to transport a mass of granite weighing hundreds of 
tons, the theory has long since been abandoned. But granting that sufficient 
power does reside in a given current or torrent to transport said boulders, this 
power would not be a cause adequate to the production of the planings and 
parallel ploughing, grooving, and stnation spoken of; for, though the transported 
boulders might plane, plough, and groove the underlying rocks, inasmuch as 
there would be nothing to retain these masses of rock in a uniform and steady 
course, the scratchings and groovings, instead of presenting the uniformity 
we behold, would be entirely devoid of system or symmetry. 
Since it has been demonstrated to be utterly impossible for - the masses of 
rocks to be transported by water alone, a theory known as the “ iceberg theory” 
has been advanced. This theory supposes that these erratics were frozen into the 
ice, and, the ice floating into southern regions, melting, dropped them wherever 
we find them. Granting the possibility of transporting the rocks in this manner, 
the other phoenomena spoken of is not accounted for; because frozen in icebergs 
which were driven about at random by the currents, or by the winds, the scratches 
