320 The American. Geologist. May, 1895 
ton county this latter phase is admirably shown. Here huge 
blocks and slabs of limestone, four feet long and six inches or 
more thick, are seen lying at all angles, apparently just as 
they fell from an overhanging cliff and were buried in the 
loose sands at its base. The sandy portion of this bed fre- 
quently becomes of considerable thickness, thirty feet or more, 
and is heavily cross-bedded. It might at times be readilj'^ 
confused with the basal portion of the Coal Measures except 
for the fact that careful search usuall}'' reveals at some point 
a layer of the characteristic compact limestone of the Saint 
Louis interbedded with it. 
In the old railroad quarry near Atwood, in Keokuk county, 
the limestones and sandstones are fairly regularly interbed- 
ded. This seems to mark the closing portion of the Verdi de- 
posits, the transition from them to the Pell a being nowhere 
marked by a sharp physical break. The signs of disturbance, 
so abundant in the one, give place to the marks of greater 
quietude in the other. The sands and broken blocks of the 
shore are replaced by the limestones and marls of the open 
sea, 
Sprinyvale beds. — Below the beds just described is a thin 
but very constant bed which has been recognized along the 
Skunk river in Washington and Keokuk counties. It is made 
up of a blue, somewhat calcareous shale, which weathers read- 
ily into a soft earthy brown mass. It is in places arenaceous 
and is usually known locally as a sandstone. It has a fairly 
uniform thickness of twenty to twentj^-five feet and is very 
rarely fossiliferous. It is well exposed at the old Springvale 
mill south of Delta in Keokuk county and shows here the blue 
shaly character as well as the weathered brown aspect. Good 
exposures also occur on Crooked creek south of Washington. 
The only fossils so far found in this bed are a few obscure 
forms which occur at Brighton. These are imperfectly pre- 
served and are in the main of only slight value for purposes 
of correlation. On the whole, however, they are such forms 
as might readily be found in either the Keokuk or Saint Louis, 
Stratigraphically the beds present closer relations with the 
overljnng Saint Louis than with the underlying Augusta and 
for the present the Springvale is placed in the Saint Louis. 
