360 HENRY B. KUMMEL 
Shawangunk conglomerate. The upper ten feet of the Decker 
Ferry series contain fossils, particularly in the lower half, which 
render necessary their correlation with the Cobleskill limestone of 
eastern New York. 
In the Green Pond Mountain region isolated outcrops of impure 
limestone occur a short distance above the Longwood shale, which 
contain a fauna that correlates them with the lower beds of the 
Decker Ferry formation, i. e., to the part referable to the Salina group. 
Rondout limestone.—Along the upper Delaware the beds immedi- 
ately above the Decker Ferry limestone and referred to the Rondout 
consist of more or less earthy shales and limestones the thickness of 
which is 39 feet. They are usually only sparingly fossiliferous, 
although in some beds the crustacean Leperditia is abundant. A 
typically marine fauna, with an abundance of brachiopods, trilobites, 
etc., 1s conspicuously absent in these beds. In general lithologic 
features this formation resembles the Rondout as developed in New 
York state, but the cement beds which are so characteristic of this 
formation farther north are not present here. 
Manlius limestone-—The Rondout is succeeded conformably by a 
somewhat thin-bedded, knotty, dark-blue or almost black limestone, 
34 to 35 feet thick where best exposed. It is the bed which constitutes 
the quarry stone of the Wallpack Ridge and its outcrop is marked by 
a line of quarries and lime kilns. It is referred to the Manlius or 
“Tentaculite”” limestone of the New York series, although well- 
preserved specimens of the characteristic fossil Tentaculites gyracan- 
thus Eaton are rare. In the lower beds there is evidence of eviron- 
mental conditions similar to those of the Rondout. In the middle 
portion, Leperditia is still abundant, but is associated with a prolific 
brachiopod fauna, suggestive of the recurrence of more typical marine 
conditions. In the upper beds Leperditia has entirely disappeared, 
and the fauna is normally marine. No beds referable to the Rondout 
or Manlius have been detected in the Green Pond Mountain region, 
although their attenuated representatives may occur. 
THE DEVONIAN 
The Devonian formations of the upper Delaware Valley are 
of marine origin and are chiefly fossiliferous calcareous shales and 
