134 Hl. M. Chance—The Millstone Grit. 
December 10th, 1880. 
Art. XVIIL—The Millstone Grit in England and Pennsylvania ; 
by H. Martyn CHANCE. 
Pennsylvania and. Ohio. , 
A survey of the Conglomerate, No. XII (Millstone grit), 
made in 1875 along the Beaver and Shenango valleys, led me 
to conclude that that rock in Western Pennsylvania is a com 
posite series of sandstones and conglomerates separated by 
shales and slates with interbedded coals, limestones, 1ron oF 
and fire clays, with a total thickness of 250-325 feet (Report ', 
* Monograph of British Silurian Brachiopoda, p. 339, pl. 50, figs. 1-14, (eh) 
{On the Brachiopoda of the Paradoxides beds of Sweden, p. 19, pl. iii, figs. 3° 
41, (1876). Idem, “Om Faunan i kalken med Conocoryphe Exsulans,” p- 27, Pl 
iii, figs. 45-49, (1879). 
¢ Bull. Soc. Geol. Fr., vol. xviii, p. 536, pl. VIII, figs. 5a-e. 
