334 Notice and Review of the Reliquiae Disuvianee. 
lest. doubts as to the evidence there is to prove that the 
surface of the earth owes its last form not to the gradual 
action of existing causes, but to the excavating force of a 
suddenly everwhelming and transient mass of waters.” 
We must not, however, attribute the origin of all vallies 
to diluvial action. In primitive and mountainous districts 
especially, “‘ the original form in which the strata were 
deposited, the subsequent convulsions to which they have 
been exposed, and the fractures, elevations and subsiden- 
ces which have affected them, have contributed to produce 
vallies of various kinds on the surface of the earth, before 
it was submitted to that last catastrophe of an universal 
deluge which has finally modified them all.” : 
_ Existing vallies, then, have been produced by three dis- 
tinct classes of agencies. 1. By the present streams, the 
bursting of lakes, &c. 2. By the last universal deluge. 
- By the original construction of the strata, and dilavi 
actions previous to the last. It may be difficult, i 
oper 
t 90se of this 
clea referable 
to all the agencies above mentioned. When, for instance, 
we find on the margin of a valley, diluvial pebbles and 
bowlders, evidently torn out of that valley, we can have no 
hesitation in ascribing its excavations to the last universal 
ecticut river ; but we cannot make it understood without 
a map and sections ; and if we mistake not, we discovely 
