Researches of McGee and Davis. 65 
’ 
margin of the province the subsidences are recorded in the sedi- 
ments deposited as the sea transgressed upon the land, and in 
some cases the amount of subsequent uplift is indicated by the 
recession of overlying deposits. In so far as these oscillations 
have been determined from sedimentary deposits, cach trans- 
gression of the sea was regarded as marking a continental depres- 
sion, and each recession a continental uplift. Within the past 
-few years, however, a complete revolution has been effected in 
the interpretation of the post-Paleozoic history of this region. 
Through the work of a few pioneers in this field the number and 
character of the principal oscillations and their position in geo- 
logic time are now fairly well known. 
The first systematic application of the new methods of re- 
search was made ‘by McGee in the middle Atlantic slope. In 
1885, in a paper on the geology of Chesapeake bay,** he pointed 
out the methods pursued and the importance of utilizing topo- 
graphic forms resulting from degradation, as well as the comple- 
mentary sedimentary deposits in interpreting geologic history. 
In 1888 + he more definitely correlated the principal oscillations 
with the sedimentary deposits, thus fixing their position in geo- 
logic time, and in a subsequent paper { he made the very impor- 
tant generalizations that all elevations have been accompanied 
by seaward tilting of the land, and that along certain axes the 
oscillations have reached a maximum amount, while along others 
both elevation and depression have been at a minimum. 
Davis§ published the results of his studies on the geomor- 
phology of the middle and north Atlantic slope shortly after the 
* The Geology of the Head of Chesapeake Bay, by W J McGee: Seventh 
Annual Report U. 8. Geological Survey, 1888, pp. 545-646. 
+ Three Formations of the middle Atlantic Slope, by W J McGee: Am. 
Jour. Sci., vol. xxxv, 1888. 
{The Lafayette Formation, by W J McGee: Twelfth Annual Report 
U.S. Geological Survey, 1891, pp. 353-528. 
Geology of Washington and Vicinity, by W J McGee: Compte Rendu 
de la Congrés Géologique International, 5th Session, Washington, 1891, 
pp. 219-251. 
2 The Rivers and Valleys of Pennsylvania, by W. M. Davis: Nat. Geog. 
Mag., vol. i, 1889, pp. 183-253. 
The geographic Development of northern New Jersey, by W. M. Davis 
and J. W. Wood: Proc. Boston. Soc. Nat. Hist., vol. xxiv, 1889, pp. 
365-423. 
The Rivers of northern New Jersey, by W. M. Davis: Nat. Geog. 
Mag., vol. ii, 1890, pp. 81-110. 
