257] F. Reeves 59 



sylvanian are the surface rocks. They comprise a series of 

 from 2000 to 2500 feet of alternating thin-bedded shales, 

 sandstones, limestones, clays, and coals. The Mississippian 

 underlies the Pennsylvanian unconformably. It is made up 

 of about 800 feet of sandstone, shales, and limestones which 

 vary in thickness from 100 to 250 feet. The Catskill forma- 

 tion is a non-marine facies of the Upper Devonian. It con- 

 sists of from 500 to 800 feet of thin-bedded sandstones and 

 red and dark-colored shales. Below the Catskill occur about 

 300,0 feet of compact shales. Underlying these are the Lower 

 Devonian limestones. 



Occurrence of the Water. Water is found in the sandstone 

 and limestone members of the above stratigraphic series. In 

 these it occurs in porous layers in which also occur oil and 

 gas. Usually there is a structural arrangement of these 

 materials. Generally the water occupies the synclines, the 

 gas the anticlines, and the oil intermediate structural posi- 

 tions. This distribution is modified by the amount of water 

 in the sands. Where they are saturated the oil occupies the 

 anticlinal areas. In the Appalachian oil fields, however, the 

 most common condition encountered is where there is but 

 sufficient water to fill up the synclines. The oil, under such 

 conditions, occupies a belt structurally higher and the gas fills 

 up the anticlinal areas. In sands that contain no water the 

 oil is found in the synclines. 



The amount of water in a sand is usually thought to be a 

 function of its depth. In general it may be stated that the 

 Pennsylvanian sands are saturated, the Mississippian sands 

 semisaturated, and the Catskill sands dry. This would appear 

 to support the idea that the water present is meteoric in ori- 

 gin. On examining the facts, however, this assumption does 

 not appear to be justified for the water does not disappear 

 with depth. Two deep wells which have penetrated the Lower 

 Devonian strata have revealed the fact that below the dry 

 Catskill sands are prolific water-bearing strata at depths from 

 5000 to 6000 feet. This occurrence, as well as the universal 

 appearance of water at all depths in other oil fields, indicates 



