212 The American Geoto</i*f. October, 1894 
existing rivers are relatively insignificant or impoverished ex- 
amples of their kind, the British geologists early found in 
their environment an easily comprehended incentive to ascribe 
the shape of the land to the action of the sea. Although this 
inference was a consequence of the insular position of the 
British school, we find among its founders, in Hutton and 
Playfair, a keener sense of the efficiency of rivers than ap- 
pears to have been enjoyed by our later great teacher, Lyell. 
It may be permissible in this connection to present the re- 
markable diversity of forms claimed for this agency by Jukes, 
who stands as an extremist of this school. Jukes's views, it 
must be said, accord pardonably with his opportunities for 
geological observation, since his lot was cast first in Ireland 
and then in Newfoundland, two insular fields ill calculated to 
inculcate those comprehensive ideas regarding the interaction 
of existing and now locally inoperative causes which it is the 
privilege of the wider ranging continental geologist to recog- 
nize, with the assignment of its due importance to each in the 
economy of geological work. It was partly owing to this cir- 
cumstance and partly perhaps to the influence of the thought 
of his contemporaries, that Jukes wrote as he did: 
But when we Feel ourselves entitled to take tor granted thai all cliffs 
at the foot of which the sea is now beating have been produced by the 
erosive action of the waves, it only requires us to admit that the land 
may have stood formerly at lower levels, so as to allow the sea to how 
over the lower parts of it, for us to seethe probability that all inland 
cliffs, crags, precipices, valleys and mountain passes, may have been 
produced in the same way And speaking generally, the prin- 
cipal features in the forms of the ground in all lands have been pro- 
duced by this widespread action.* 
The same author states dogmatically, as late as 1862 : 
"Rivers form their own beds, but not their own vallej^s."! 
These quotations are directly opposed to the views of to-day, 
as they are to the earlier and clearer understanding of the 
competency of rivers shown in Playfair's "Illustrations of the 
Huttonian Theory.'' The studies of continental geologists 
within the past two or three decades have done much to revise 
opinion upon this subject. Indeed, the work of reconstruct- 
ing the marine theory of baseleveled lands was begun by Ram- 
•T. B. Jukes, The Student's Manual of Geology, second ed.. Edin- 
burgh, ISC.-.', p. 101. 
f()p. fit., p. 1 (»•"). 
