MOLHORS ABSLRAGLS: 979: 
are chiefly illustrative of the topographic features of the county. The 
economic products of the county justly receive a fair share of atten- 
tion. 
Geology of Linn County——By WitLtiAM Harmon Norton. This 
paper contains several paragraphs of general interest. The Devo- 
nian series in the county is divided into the Cedar Valley stage 
and the Wapsipinicon stage. The latter embraces the Upper Daven- 
port beds, equivalent to the Gyroceras beds of Calvin, and to the 
Upper Helderberg of Hall, and the Carboniferous of Barris; the Lower 
Davenport beds not before delimited; the Independence Shales described 
for the first time in natural sections, and a new basal terrane termed 
the Otis beds, whose characteristic fossil is Spzrifer Subumbonus, Hall. 
Above the Le Claire, the highest member of the Upper Silurian hitherto: 
recognized, were found two new formations, transition beds to the 
Devonian and named the Bertram and Coggan. 
Of special interest to glacialists are the sections and maps showing 
the form and structure of the unique glacial hills of this region, the: 
Paha. They are treated as loess-capped drumloid accretions of till. 
Geology of Van Buren County—By C.H.Gorpon. Van Buren 
county lies on the southern border of the state with one county (Lee) 
lying between it and the Mississippi River. The main drainage is 
effected by the Des Moines River which cuts it diagonally from the 
northwest to the southeast. The surface consisted originally of a 
broad level plain having a gradual slope toward the southeast. 
The indurated rocks belong entirely to the Carboniferous forma- 
tions, including the Burlington, Keokuk, Saint Louis and Lower Coal 
Measure stages. The Burlington is represented by the upper chert 
beds, to which the name Montrose cherts is here given. ‘The strati- 
graphy of the region is described in considerable detail, and errors of 
previous writers corrected. Some ofthe points of interest brought out 
in the paper are the following: a revision of the classification of the 
Keokuk and Saint Louis formation, and the plane of separation between 
these more satisfactorily defined (See Journal of Geology, Vol. III, No. 
3, £895); the origin of the ox-bow bend of the Des Moines (a topo- 
graphic map of the area is given showing terraces up to 145 feet above 
the river); the erosion unconformity between the Lower Carboniferous 
and the Coal Measures. 
Geology of Keokuk and Mahaska Counties —By H. Foster Bain. 
These two adjoining counties lie in the southeast central portion of 
