GEOLOGICAL ABSTRACTS 
THE STATUS OF SEDIMENTATION IN IOWA 
A. C. TROWBRIDGE 
Iowa need not be ashamed of the part her geologists have 
played, either in the past history of sedimentation, or in the re- 
cently renewed American activity on this important, but too long 
neglected subject. There being no igneous rocks in situ within the 
state and practically no exposures of metamorphic rocks, all the 
work which has been done on the geology of the state during the 
years is more or less closely related with sedimentation. The more 
recent investigations of breccias by Professor W. H. Norton, of 
gumbotils by Dr. George F. Kay, of Pennsylvanian stratigraphy 
and structure by Dr. John L. Tilton, and of clays by Dr. Sidney 
E. Galpin, constitute important contributions to knowledge of sedi- 
mentary rocks and the conditions under which they are formed. 
At the State University there is a research course in sedimenta- 
tion and a sedimentation laboratory is in process of establishment. 
SCHEDULES FOR THE FIELD DESCRIPTIONS OF 
SEDIMENTARY ROCKS 
A. C. TROWBRIDGE 
An explanation of the schedules recently reported by a subcom- 
mittee of the committee on sedimentation of the National Re- 
search Council, and presentation to each of those present of mime- 
ographed copies of the introduction to these schedules, and of 
printed copies of the schedules themselves. These materials were 
furnished the writer by Dr. M. I. Goldman, Chairman of the com- 
mittee. 
Department oe Geology, 
State University oe Iowa. 
AN IOWA CAMBRIAN EURYPTERID 
O. T. WALTER 
Associated with dismembered parts of Dikellocephalus minne- 
sotensis in the St. Lawrence limestone, at Lansing, Iowa, are parts 
