FORMATIONS OF SILURIAN AGE. Lene 
2 A’®. Thin-bedded, calcareous shale. Ditto Tne 
1. Leperditia alta (Con.) ? 
2 A’*®. Earthy limestone, weathering to a buff color. The 
“Peth stone” of Professor Cook’s report. 5 ft. 
1. Undetermined foraminifera or ostracodes. 
2 A**, 'Thin-bedded, crumpled shale, with some bands of 
denser limestone. Loi tt. 
1. Leperditia alta (Con.). ; 
This formation occurs at various localities throughout the entire 
length of the Wallpack ridge in New Jersey, but it is usually covered 
in the sections, and no detailed study of it has been made, except at 
the Nearpass quarry. 
The original definition of the Rondout formation by Clark and 
Schuchert* is not entirely satisfactory. At Rondout, New York, 
where the typical section of the formation occurs, there are two 
cement beds quarried or mined, which are separated by a series of 
strata which do not possess the necessary properties for the manu- 
_ facture of cement. Clark and Schuchert seem to have included this 
entire series of strata—the lower cement bed, the intermediate beds. 
and the upper cement bed—in their Rondout formation. The inter- 
mediate beds are not abundantly fossiliferous, but a careful search 
during a short visit to the locality brought to light several species, 
all of which are characteristic of the Decker Ferry fauna of New 
Jersey, and it is believed that the strata separating the two cement 
beds at Rondout are to be considered as an extension of the Coralline 
limestone of New York and of the Decker Ferry formation of New 
Jersey. In this case the lower cement bed at Rondout may be 
directly correlated with the Bossardville limestone of New J ersey, 
which leayes only the upper cement bed to be included under the 
name Rondout formation, and it is in this restricted sense that the 
name of the formation is used in the New Jersey section. The beds 
lying between the Decker Ferry formation below and the Manlius 
limestone above are believed to be the southern extension of the upper 
cement bed at Rondout. In its southern extension the cement bed 
proper has become reduced in thickness, so that in the Nearpass sec- 
tion it is represented only by bed 2 A*°, which was described by Pro- 
fessor Cookt as the “Peth stone,” but with the thinning of the cement 
bed proper, to the south, the associated shales and limestones have 
become increased in thickness. 
* Sci. N.S., vol. X., No. 259, pp. 874-878, and Am. Geol., vol. XXV., p. 119. 
t Geol. N. J., 1868, p. 159. 
