454 J.W. Powell's Survey of the Rocky Mountain Region. 
should visit the field again for the purpose of determining 
certain doubtful points in the geological structure, and to in- 
sert on the maps the position of the several towns and roads 
established in that region since the discovery of gold, and Mr. 
ewton was employed for this purpose. He had been in the 
field but a short time when he was prostrated by the sick- 
ness which resulted in his death. Previous to his departure he 
completed his report on the geology of that country, and the 
po A been placed in the hands of the engraver; the whole 
embodying all the facts discovered up to that time. Thus, 
happily, his work will not be lost. It is expected that his 
report will be published during the present winter, in the 
shape in which it was left by him. 
The death of Mr. Newton makes a serious break in the 
ranks of the younger and more active geologists of America. 
€ possessed rare abilities, had much experience in field opera- 
‘ions, and had received thorough and wise training, and his 
work in other fields had exhibited his ability. But the great 
work of his short life will doubtless be his report on the geol- 
ogy of the Black Hills of Dakota. 
During the past six years one branch of the work of the 
survey has been considered of paramount importance, namely, 
the classification of lands and the subjects connected therewith. 
The object has been to determine the extent of irrigable lands, 
timber lands, pasturage lands, coal lands and mineral lands. 
In general the lands that are cultivable only through irrigation 
are limited by the supply of water. There are some excep- - 
tions to this. Where streams are found in narrow valleys or 
run in deep cafions, the limit of agricultural land is determined 
by the extent of the areas to which the water can be conducted 
with proper engineering skill. In the study of this subject 
interesting and important problems have arisen, an 
many valuable facts have been collected. 
From the survey of the timber lands one very important 
fact appears, that the area where standing timber is actually 
found is very much smaller than the areas where the condi- 
tions of physical geography are such that timber should be 
found as a spontaneous growth—that is, the area of timber is 
but a small fraction of the timber region. The destruction of 
timber in such regions now found naked, is due to the great 
fires that so frequently devastate these lands: and the amount 
of timber taken for economic purposes bears but an exceed- 
ingly small ratio to the amount so destroyed. Hence the 
Important problem to be solved is the best method by which 
these fires can be prevented. 
