32 ECONOMIC GEOLOGY OE AMITY QUADRANGLE, PA. 
vania and the Catskill Mountain region, is several hundred feet thick, 
but which in this region is thinner and is dovetailed into the upper 
part of the Chemung formation. 
The general character of the group containing the red beds can be 
seen from the well sections given in PL II (p. 22). The individual 
beds vary from 10 to 60 feet in thickness and the total amount of red 
material in any one section is usually between 75 and 150 feet. In the 
Latrobe quadrangle the thickness reaches 300 to 400 feet and the 
member is more of a unit, so that it might almost be termed a forma- 
tion, but in the direction of the Amity quadrangle it becomes thinner 
and dovetails into the Chemung formation proper. This method of 
dying out explains the great variation of the red beds in the different 
sections and why they do not always occur at the exact top of the 
formation. 
Sandstones. — Between the horizons of these red beds several oil 
and gas sands, notably the Gordon, Fourth, and Fifth, are frequently 
reported. The very fact that these sands occur interstratified be- 
tween red beds, which appear and disappear and sometimes thicken 
up to the exclusion of the sands, indicates the i ion persistency of most 
of the sands in this region. The wells penetrating these beds are] 
located in the southeastern part of the quadrangle and nothing is 
known of the behavior of the beds in other sections. It is considered 
very probable that toward the northwest they are more broken up, and 
the Gordon and other sands become more persistent. 
Most of the sands in the Pocono formation, commonly recognized by 
drillers, are shown by records to be encountered rather regularly, and 
are therefore considered fairly persistent beds. As the drill descends 
into the undertying rocks, however, it penetrates beds of more and 
more variable character; and even the most important oil and gas 
sands are encountered with much less regularity than in the higher 
formations. These variations are so great that it is now considered 
probable that the sandstone horizons in the upper part of the Chemung 
formation are not persistent members underlying the whole area, but 
are in the nature of lentils, similar to the sandstone lentils of the 
Allegheny and Conemaugh formations outcropping at the surface. 
This is in harmony with the character of the Chemung formation in 
regions where it outcrops. 
The principal sands recognized by drillers in the Chemung forma- 
tion are (from the top downward) the Gordon Stray or Nineveh Thirty- 
foot, Gordon, Fourth, Fifth, Bayard, and Elizabeth. Of these the 
Bayard and Elizabeth are the only ones which are at all persistent, as 
they occur below the variable Catskill beds. A description of the 
various sands is given in the section on oil and gas (pp. 47-59). 
