THE PROGRESS OF GEOLOGY IN 1843. 
vii 
of sucli facts as will suport the views of geologists on the sub- 
ject of the transportation of erratic blocks — their distribution, 
and their origin. An interesting essay, on a subject closely con- 
nected with this, was read at the ] 842 meeting of the Associa- 
tion of American - Geologists, and amongst the facts therein re- 
corded of the nature of icebergs, as seen in their progress south- 
ward, both near the shore and in the middle of the ocean, was this 
that large masses of rock and quantities of earthy matter were 
imbedded in the sides of the icebergs in question, the water for 
at least a quarter of a mile round them being full of mud, stirred 
up from the bottom and the sides of the mass. — (Vol. II. p. 35.) 
The general description here made use of applies to all instances, 
individually — the inference drawn from these facts, and which is 
given in the paper alluded to, is, in our opinion, a practical ex- 
position of the circumstances under which these erratic blocks 
were and are deposited. The general rules of their disposition^ 
will only be better understood when the general problem of pe- 
riodical tides is more completely solved. 
In immediate connection with this elucidation, we would place 
the conclusion at which Prof. H. D. Rogers has arrived during 
his surveys of the Appalachian Chain, viz : — that the striae and 
furrows observed on the summit of most of the rocks in that 
locality are connected with the question of drifts not of glacial 
action. This adds other most important evidence of the gene- 
ral effects of diluvio-glacial force. 
This grand question then, resolves itself into the following 
divisions. 
The disposition of Erratic blocks. 
The disposition of moraines. 
The phenomena of raised beaches, 
. Detrital phenomena in general, 
all of them relating purely to the tertiary epoch of geological 
change. The conclusion thus arrived at, proves "that no one 
Diluvio-glacial action, in- 
cluding 
