Maryland Geological Survey 73 



cardellahellistriaia (CoriTcad) , PI curoio in aria (Bembexia) sulcomarginata 

 Conrad. 



On the National Road in Gilpin, 200 3'ards west of the bridge over 

 Town Creek, the following species were collected in the arenaceous layers 

 of the upper Romney : Stropheodonta (Leptostrophia) perplana (Con- 

 rad), Schuchertella sp., Chonetes mucronatus Hall, Chonetes lepidus Hall, 

 Tropidoleptus carinattis (Conrad), Spirifer mucronatus (Conrad), Am- 

 hocoelia umbonata (Conrad), Paracydas lirata Conrad, CyrtoUtes {Cyr- 

 tonella) mitella Hall. 



The lithological appearance and fauna of this zone are those of the 

 typical New York Hamilton in which stage it clearly belongs. It is in the 

 upper part of the Eomney formation. 



Although the exact contact of the Hamilton and Genesee shales is not 

 shown, still the covered interval is not great and it is thought that the 

 thickness of the Eomney formation along the National Road through 

 Gilpin is given quite accurately. The eastern ridge crossing the road in 

 Gilpin was considered the upper sandstone of the Eomney which is 

 about on the line of strike with the highest exposure of the formation 

 shown on the bank of the creek. The rocks immediately succeeding this 

 sandstone are covered but allowance was made for the shale at the top 

 of the Romney while the base of the formation is clearly marked at the 

 western end of Gilpin by the Oriskany sandstone. There is, apparently, 

 no folding in this distance and the direction is nearly at right angles to the 

 strike so that the locality is favorable for measuring the thickness of the 

 formation. The average dip of the exposures from the top of the Oriskany 

 sandstone to the top of the Romney formation is about 30°. The paced 

 distance from the top of the Oriskany sandstone to the top of the lower 

 sandstone near the corner of the road leading north in Gilpin is 2080 

 feet which gives a thickness of 1040 feet. The paced distance from the 

 base to the point at which the top of the Romney was drawn above the 

 second sandstone, is 3180 feet which gives a thickness of 1590 feet for the 

 formation. The same distance measured by the buggy wheel gave a hori- 

 zontal distance of 3205 feet and a thickness of 1C02 feet. An independent 

 measurement at this localitv bv Rowe gave a thickness of 1605 feet for 



