312 CEMENT MATERIALS AND INDUSTRY. Tbill. L'43 
So far as composition is concerned, both the marbles and the ordi 
nary limestones are well suited for use as Portland cement materials, 
Fuel, however, is expensive; there are no good local markets l'oi 
cement and cement products, and satisfactory clays are rather difficult 
to obtain. Commercial conditions, therefore, seem to rule these other- 
wise excellent Vermont limestones out of consideration. If conditions 
were different, a flourishing- Portland-cement industry might be estatM 
lished, as a cement plant could utilize the enormous amount of wasfclJ 
material from the marble quarries. 
PORTEAXI) CEMENT RESOURCES OF VIRGINIA. 
By R. S. Bassler. 
PORTLAND CEMENT MATERIALS. 
Four prominent sources of Portland cement material appear in Yirj 
ginia. Listed in geologic order, these are: 
4. Tertiary soft limestones ("niarls"). 
3. Greenbrier (Lower Carboniferous) limestone. 
2. Lewistown (Lower Helderberg) limestone. 
1. Ordovieian (Trenton, etc.) limestones. 
The Tertiary limestones, often called "marls," but entirely differed 
from the fresh-water marls of northern States, occur in eastern oi 
tidewater Virginia. At present their distribution and composition an 
not sufficiently known to justify discussion. The remaining thret 
groups occur in western Virginia, in the Great Valley and its foothills. 
Of these three the Lewistown limestone is now used in Port lane 
cement manufacture at Craigsville, while the Greenbrier limestoB 
will probably be an important source of cement material in south 
western Virginia. The general distribution of both these formations ij 
shown in the accompanying map (PI. XV), but little is known concern 
ing the details of their composition and local distribution. Wit! 
regard to the fourth and most important group — the Ordovieian lime 
stone — the case is different, for a ver} 7 careful examination has beet 
made of the Trenton and other Ordovieian limestones in the valley o: 
Virginia. 
For many years the argillaceous Trenton limestones of the Lehigl 
district of Pennsylvania have furnished the raw material for the manu 
facture of the greater part of the Portland cement output of th 
United States. Because of this enormous output the argillaceou 
limestones of this relatively small district have assumed a great eco ' 
nomic importance, and the occurrence of the same rock in other se< i 
tions of the countiy is not without considerable interest. 
In the early part of the held season of 1904 the writer spent s] 
weeks in the Lehigh and Lebanon valle} 7 s of Pennsylvania in a gener 
study of the paleontology and stratigraphy of the Ordovieian stral 
but particularly in mapping the distribution of the Trenton limesto 
or cement rock. Later in the season about three weeks were devot< 
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