Reviezv of Recent Geological Literature. 55 
achian field, his experimental master}- of the dynamics of rock move- 
ment, his ability to draw broad generalizations and his unusual lucidity 
of statement, are able to give to it. The paper presents an invaluable 
reading lesson for college students of historical geology. 
Part II. contains The Second Report on the Highways of Maryland 
by Harry Fielding Reid an.d A. N. Johnson. The first report present- 
ed the condition of the highways throughout the state and outlined 
methods of improved road making. 
The present report gives an account of the work which has been 
conducted under the supervision of the Highway Division of the Mary- 
land Geological Survey : It describes some new methods of testing 
road material which have beer, devised in the laboratory of the Divis- 
ion, and closes with a report of the Baltimore County Roads Engineer. 
The report makes very clear the important fact that the highways 
of Maryland can be permanently improved by the intelligent use of 
means now available in the state without additional cost. The work 
of this division of the Survey is plainly of immediate practical value 
to the state. 
Part HI. comprises a Report on the Clays of Maryland by Hein- 
rich Ries. The report opens with an elaborate discussion of the or- 
igin, properties and uses of clays with special reference to those of 
Maryland. Dr. Ries also discusses methods of testing clays and shows 
bow qualities injurious to the clay for commercial purposes can be 
counteracted by the addition of proper ingredients. 
The second part of the report deals with the geologic distribution 
ar.d character of the Maryland clays and their relation to transpor- 
tation facilities. 
Maryland ranks eleventh in the list of clay producing states and 
seventh as a producer of pottery and yet possesses a very large unutil- 
ized supply of plastic material. It is the aim of this part of the re- 
port to bring to public knowledge the distribution and character of this 
unutilized material. A bibliography of accessible publications or, clay 
and a directory of Maryland clay workers are appended. 
This exhaustive report on Maryland's clay wealth by an e.xpert in 
the subject must possess great interest for the practical operator. All 
the reports are well and fully illustrated by maps, cuts and photo- 
graphs. F. B. 
Les roches volcaniques de la Martinique. A. Lacroi.\ (Comptes 
Rendus. May- igo2.). Prof. Lacroix here recalls descriptions of 
the rocks of Martinique published by himself in the Comptes Rendus 
in 1890. They were specimens of the collection of Ch. Sainte-Claire 
Deville preserved in the College de France at Paris. He showed that 
the presence of hypersthene in the volcanic rocks of Martinique and of 
Guadeloupe is an essential and almost constant character. 
'"The earlier volcanic rocks are divided into three groups : dacytes, 
andesytes and labradorytes. They form dykes, flovs and conglomer- 
ates accompanied by beds of ash. 
