Review of Recent Geological Literature. 115 
penetrating routs; the deterioration or exhaustion of cultivated hinds bj 
faulty methods of farming; and the precautions needed to insure per- 
manent productiveness. The pressure of the plow on the part of the 
soil beneath that which if overturns is shown to be unfavorable for the 
best tillage, and the invention and substitution of some machine capa- 
ble of working over and thoroughly loosening tin- soil as when it is 
spaded by the gardener are strongly recommended. An outline of this 
subject had been presented by the author in the final essay of his vol- 
ume. "Aspects of the Earth," a year or two previous to its elaboration 
for this report. \v. u. 
The Lafayette Formation. By W .1 McGee. Pages 347-521; plates 
xxxii-xli. and figures 28-72. (Accompanying the Twelfth Annual Re- 
port. V. S. Geol. Survey.) Upon an area of about 100,000 square miles 
of the coastal plain in the Atlantic and Gulf states and of the Mississip- 
pi valley, extending north to the limits of the glacial drift in northern 
New Jersey and southern Illinois, the loam. sand, and gravel beds of 
the Lafayette formation constitute the present surface: and upon areas 
aggregating twice as much more this formation has been removed by 
erosion, or lies concealed beneath the Columbia deposits. In thickness 
the Lafayette beds are described as ranging from a mere veneer over 
many interstfeam tracts to 200 feel or more about the mouth of the 
Mississippi, the variation being in general directly proportional with 
the volume of neighboring rivers and inversely with the extension in- 
land. In structural relation the Lafayette is separated from the newer 
( 'olumbia formation by t he strongest unconformity of 1 he coastal region, 
representing the erosion of probably half the volume of the Lafayette 
formation and profound trenching of subjacent formations along the 
larger waterways: while the contact with all the underlying formation'- 
indicates that during pre-Lafayette time the coastal plain was a land 
surface and was wrought into a configuration much like that existing 
to-day. As to I heir manner of deposition. Mr. McGee holds that the 
Lafayette beils were laid down in the shallow borders of the Atlantic 
ocean and Gulf of Mexico, being brought by rivers which are still in ex- 
istence, when the land stood from 200 to 800 feel lower than now. and 
when the sea and gulf extended from 50 to .Mm miles inland of the pres- 
sent coast. In age this formation is regarded as many limes older than 
the earliest known Pleistocene and glacial deposits, bill much newer 
t ban any other well defined formation of the coastal plain. To account 
for the deposition of the La lav ette beds, the author supposes their areas 
to have been depressed beneath the sea. It is noteworthy, however, 
that no definite beaches, marine fossils, or other proofs of the presence 
of the sea have been discovered: and the ureal amount of erosion follow- 
ing the Lafayette deposition required an important continental uplift. 
A simpler view of the epeirogenic movements, closing the Tertiary 
era and inaugurating the Quaternary, seems to the present reviewer to 
!>'■ found in ascribing the Lafayette formation to deposition on land 
areas h\ Hooded rivers descending from the Appalachian mountain 
