METHUEN’S GEOLOGICAL SERIES 
General Editor : J. W. GreGoRy, D.Sc, F.R.S,, 
Professor of Geology in the University of Glasgow 
THE PRINCIPLES OF PETROLOGY: an. Intro- 
duction to the Science of Rocks, By G. W. TYRRELL, 
A.R.C.Sc, F.G.S., F.RS.E,, PhD. With 78 Dia- 
grams. Crown 8vo. 10s, net. 
THE ELEMENTS OF ECONOMIC GEOLOGY. By 
Professor J. W. Grecory, With 63 Diagrams, 
Crown 8vo. 
GENERAL STRATIGRAPHY, By Professor J. W. 
GREGORY and B, H. BarrerT, M.A. B.Sc. “With 
Diagrams. Crown 8vo. In preparation. 
GEOMORPHOLOGY. By F. Drrevuawm, O.B.E,, 
M.A., Gonville and Caius College, Cambridge. With 
Diagrams. Crown 8vo, In preparation.