608 REVIEWS 
Oil Fields of the Texas-Louisiana Gulf Coastal Plain. By N.M. 
‘FENNEMAN. (U. 5S. Geological Survey, Bulletin No.-282.) Pp. 
146, 11 plates. Washington, D. C., 1906. 
The oil of this region generally occurs beneath low mounds. At 
depths of 800 to 1,600 feet these mounds contain three substances that 
are not found in drill-holes away from the mounds, namely: (1) crystalline 
limestone, frequently dolomitic and usually porous or cavernous; the 
caverns are filled with oil and frequently they are lined with sulphur crys- 
tals; (2) gypsum, both the massive rock and as an admixture in sands and 
clays, occuring nearly always below the limestone; (3) rock salt and salt 
solutions impregnating sand, occuring below the gypsum. The oil is 
associated with the limestone and with the overlying unconsolidated sands. 
The position of the mounds is marked by rising ground water as indicated 
by the temperature and salinety of the water. It is thought that these 
rising waters have introduced and segregated the limestone, gypsum, and 
salt under the mounds. Possibly the pressure extorted during the growth 
and alteration of the bodies of limestone, gypsum, and salt has been suff- 
cient to raise the mounds. Ce WeMe 
The Constitution of the Interior of the Earth as Revealed by Earth- 
quakes. By R. D. O_tpHAM. (Quarterly Journal of the Geo- 
logical Society, Vol. LXII, 1906, pp. 456-73. London, 1906.) 
The author agrees with most recent seismologists in believing that the 
core of the earth does not transmit tremors with the facility of the rest of 
the planet. He does not suggest whether this inability to transmit waves 
is due to a composition of iron, compressed gas, or other substance. The 
central core occupies about four-tenths of the diameter of the earth. ‘“‘The 
interior of the earth after the outermost crust of heterogeneous rock is 
passed, consists of a uniform material, capable of transmitting wave- 
motion of two different types at different rates of propagation; this material 
undergoes no material change in physical character to a depth of six- 
tenths of the radius.” fo CW. W. 
The Geological Map of Illinois. By Stuart WELLER. Illinois State 
Geological Survey, H. Foster Bain, Director. Bulletin No. 1. 
Urbana: University of Illinois, 1906. 5 
This is a. provisional geological map in twelve colors, scale 12 miles 
to the inch. It is accompanied by 25 pages of text descriptive of the forma- 
tions and structure. ects CW. Wiss, 
