WePRECULIAR DEVONIAN DEPOSIT IN NORTHEAS?- 
ERN ILLINOIS 
THE village of Elmhurst is in the eastern edge of DuPage 
county, Illinois, on the Chicago and Northwestern Railway, fif- 
teen miles west of the Wells Street Station in Chicago. On the 
north side of the railway track, about one mile west of the 
station, are the Elmhurst quarries. The rock quarried, which 
is the buff or bluish Niagara dolomite of northeastern Illinois 
and Wisconsin, has been excavated to a depth of about thirty 
feet, 
At this locality the limestone is much fractured by two sets 
of gentle folds whose axes have a general north-west south-east 
and north-east south-west direction, joint cracks being well 
developed. Some of these cracks are several inches in width, 
and are in general filled with a black or blue clay. At one 
point, in the south-east face of the quarry, about eighteen feet 
below the glaciated surface of the rock, one of these joints is 
somewhat enlarged to form a narrow triangular opening about 
six inches in width at the base and about sixteen inches in 
height. This opening, instead of being filled with clay, as are 
all the other larger joints in the quarry, is filled with a breccia 
composed of angular fragments of the adjacent limestone, 
imbedded in a dark brown arenaceous matrix. This matrix is 
abundantly fossiliferous, containing immense numbers of fish 
teeth, and a smaller number of Lzngwla shells and other brachio- 
pods, which indicate its Devonian age. 
The situation of this most peculiar occurrence of Devonian fos- 
sils, deeply buried in the Niagara limestone, is shown in the 
accompanying illustrations. Figure 1 is a near view, showing 
the Devonian material filling the triangular opening to the left 
of the hammer. Figure 2 was taken from a greater distance, in 
order to show the position of the opening in the face of the 
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