94 EK. ORTON—GEOLOGICAL PROBABILITIES AS TO PETROLEUM. 
could be generated or for the heat that should effect the dry distillation 
of organic matter or for a hiding place for the carbon residue that must 
necessarily attend the process of destructive distillation. If the dark 
color of the limestone is referred to the carbon residue, then such residues 
are found without end in all dark colored rocks. 
The stratum that here underlies the Potsdam sandstone is, as I have 
already said, a dark limestone, never more than 40 feet in thickness and 
sometimes much less. Fragments of the limestone 2 to 3 inches in 
length have occasionally been brought up from the wells, and in them 
we are able to study the character of the stratum. Like most deep lime- 
stones, it is Gompact and hard to drill. Because of this character, it has 
sometimes been named “ black granite” in the well records; but there 
is not a trace or hint of metamorphic action about it, The contrast be- 
tween the dark limestone and the red granite that underlies it is always 
immediately apparent to the driller. Innumerable but unidentifiable 
fragments of trilobite crusts make a prominent part of its substance. 
There seems to be very little material in it from which petroleum pro- 
duction could be maintained even by dry or destructive distillation. 
A dozen or more other wells have been drilled to the granite in the 
same region. All of them agree in their records. ‘The two principal strata 
below the Trenton limestone are the Potsdam sandstone and the dark 
limestone, already described. The drillings brought from these horizons 
seem normal in every respect. Certainly there is no hint of any trans- 
formation by heat. ‘‘The smell of fire has not passed on them.” There 
is no carbon residue. The bituminous products found in them cannot 
therefore owe their origin to the usual form of destructive distillation. 
In following the discussion to this point, I come upon a theory that is 
sometimes met in the speculations of our day. It is to the effect that the 
great stocks of our oil fields—the oil fields of Pennsylvania, for example, 
distributed through a half dozen distinct horizons and through thou- 
sands of feet of vertical range—have all been derived from a common 
and deeply buried source; and, further, that both gas and oil have been 
purified in the process of ascent, the highest oil in the vertical series 
being the highest in chemical character as well. 
INABILITY OF PETROLEUM AND ITs DERIVATIVES TO RISE FROM ONE 
FORMATION TO ANOTHER ~ 
I remark, therefore, in the fourth place, it is probable that petrolewm 
and its derivitives are unable to rise in the geological scale from one porous for- 
mation to another. In other words, the principal deposits are hermetically 
sealed in the strata that contain them. 
