152 
ices for no other compensation than their traveling 
expenses, 
In the report for 1870 Dr. Newberry writes: 
The fossil fishes and fossil plants found in the 
sbate have been deseribed by myself. They have 
been drawn by Mr. T. Y. Gardner and Mr. G. K. 
Gilbert in a style that has not been surpassed in 
this country, and some of their work is equal to 
any of a similar character done by the best Euro- 
pean draughtsmen (page 8). 
This volume contains a short report by Gil- 
bert on three counties in the northwestern part 
of the state.2 A fuller report on the same dis- 
trict is attached to a report on the surface geol- 
ogy of the Maumee Valley, found in Volume 
1, of the final reports of the Newberry survey. 
This writing, published in 1873, contains six 
maps, evidently all his own work. The first 
two maps show the beaches of the ancient gla- 
cial waters in the Maumee Valley, and the cor- 
relation of the highest shore with the pass at 
Fort Wayne. 
These fine maps are the first ever made in 
delineation of ancient lake beaches and corre- 
lation with the controlling outlet. The field 
work for this report was done in 1869 and 1870, 
when he was only twenty-seven years of age. 
At this time Gilbert did not recognize the re- 
ceeding ice sheet as the dam that held up the 
ancient waters, but he did clearly postulate 
deformation of the earth’s surface as one 
cause of the variation of levels. He says (page 
551): 
The more general conclusion that the system of 
raised beaches signify a suecession of flexures of 
the earth’s surface, rather than successive stages 
of subsidence due to the gradual removal of a 
barrier of tide water, or the gradual wear of a 
barrier of stone, does not rest on this single fact. 
Even then he knew something of the change 
of levels in the Ontario basin, for he immedi- 
ately says, in citing other similar facts: 
“There is evidence that Lake Ontario, at 
Rochester, N. Y., has stood 70 feet lower than 
it does now” (page 552). Some sentences in 
the same connection illustrate his capacity for 
generalization. 
2 Part VIL, pp. 485-499. 
SCIENCE 
[N. S. Von. XLVIII. No. 1235 
While these facts abundantly prove that a 
simple theory of gradual drainage, by the eleva- 
tion en masse of the lake regions, is entirely inade- 
quate, they are too fragmentary to define clearly 
the general synchronism and sequence of the local 
movements to which they testify. Nevertheless, it 
is something to have learned that the writhing of 
the surface of the earth, which has in the ages so 
many times remapped the continents, has also been 
the great immediate cause of the transformations 
of the great lakes, and that, continuing through 
the latest distinguishable geological epoch and its 
prolongation the historical, it has now ceased. 
Dr. Newberry was the first geologist to recog- 
nize the ice barrier as the cause of the high- 
level waters in the Laurentian basin, and it is 
interesting to find a footnote over his initials, 
at the bottom of the same page (552), reading 
as follows: 
In the discussion of these facts cited by Mr. Gil- 
bert, and others of similar character, it should be 
remembered that the retreating glacier must have, 
for ages, constituted an ice dam that obstructed 
the natural lines of drainage, and may have main- 
tained a high surface level in the water-basin 
which succeeded it. 
The substance of Gilbert’s report in the 1873 
volume of the Ohio Survey had previous publi- 
cation by permission in the American Journal 
of Science in 1871.2 An abstract was also 
printed in the proceedings of the New York 
Academy of Sciences of February 20, 1871 (pp. 
175-178). 
In 1871 Gilbert joined the Wheeler survey 
of the western territories and began the many 
years of work in the far west. From 1875 he 
was on the survey under Major Powell. The 
United States Geological survey was organized 
in 1879, with Clarence King as director, and 
young Gilbert became a member. From that 
time to his death, May 1, 1918, he was continu- 
ously on the national survey. 
Gilbert was not a prolific writer, as compared 
with others and judged by his work and ability. 
Down to 1891 the bibliographic list carries 70 
titles, four of which have associated authors. 
His initial publication, in recognized geo- 
logic mediums, was in 1871, on the Cohoes 
mastodon in the twenty-first annual report of 
3 Vol. 1 of third series, pp. 339-345. 
