266 F.. Prime, Jr.— Lower Silurian Fossils. 
continuity have occurred, to be succeeded by another layer of 
the same material? 
While the greater portion of the limestone has in all proba- 
bility been formed in deep water, we have one instance in a 
quarry at Uhlersville on the Delaware where it must have been 
formed as a beach, since we find here distinct traces of ripple 
marks along the entire face of the quarry, some sixty feet high 
and fifty feet deep, the strata being tilted nearly vertically. 
It has been generally supposed that the limestone dips almost 
universally southward; and while this view holds good for 
orthampton county, except at the junction of No. II with the 
No. III slates and ‘along the north flank of the South Moun- 
tains, it is not the case in Lehigh county; for here we find 
northwest dips, more especially along an axis which is pro- 
longed some distance into Northampton county, a short distance 
As a general thing the limestones pass conformably under the 
“No. III slates, and the few exceptions where the slates dip 
toward the limestones, and the latter away from the slates can 
readily be explained by an overturning of the beds toward the 
south, by which means as in the slate ¢ uarry close to and south 
of Ironton the slate apparently passes conformably below the 
limestone. 
Overlying the No. IT limestone occurs the Trenton limestone 
which is more fossiliferous and contains such characteristic 
fossils as Cheetetes Lycoperdon and Orthis pectinella as well as the 
stems of an encrinite. It was first found about a mile south of 
This limestone resembles. in appearance the No. II, being 
however more compact and not at all crystalline, and of a gray 
black color. 
There has been no apparent sudden break between the two, 
but the transition has been a nal one, This was to be ex- 
pected if the subsidence of the sea-bottom was steady and slow. 
_ An examination of the beds between Ironton in Lehigh county 
and the Delaware River, as close to the junction of the limestone 
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