364 S. F. Peckham on the probable origin 
Southern California, of which I shall speak hereafter. To 
this also, without doubt, are more nearly allied certain veins 
said to occur in Miocene sandstones near the junction of the 
White and Green rivers, Colorado.* 
All observers agree that the veins first mentioned are true 
cutting veins, at, or nearly at, right angles to the planes of 
the strata which they intersect. In most instances the enclos- 
ing rocks present evidences of metamorphosis, in others they 
are unaltered, and in others still the metamorphosis has oblit- 
erated the planes of stratification, the rocks becoming crystal- 
line. It is further their unanimous opinion that the mass was 
injected, and from below upward ; also that the mass was in_ 
either a fluid or semi-fluid condition. Prof. Hitchcock believes 
that the Albertite has been injected at two distinct periods. 
He also describes ‘“ horses” or enclosed pieces of the wall rock, 
as common in the vein. Prof. Wurtz describes one of these 
masses as occurring in the Grahamite, but a few feet below the 
cavity from which it fell. The vein of Albertite has been 
mined to the depth of a thousand feet without diminishing in — 
thickness ; it forms the crown of an anticlinal, the walls press- 
ing against it with sufficient force to granulate the mineral, 
and crush large sticks of timber as they close behind the miners. 
In all these veins the lines of demarcation between the “veins” | 
ing no intervening 4 
ee 
as they both yield paraffine, but must have been derived, i : 
rived from petroleum at all, from the more stable class repre 
‘sented by those of Pennsylvania which thicken by evaporation, 
or from an oil partaking of the characters of those of both 
res ons, os 
Let the prior existence of a subterranean pool of petroleum 
be alu ted The fissure is formed and the oil enters it. In 
the case of the Albertite, what held the walls asunder peer 
the oxydation was in process of completion—a process Wit" 
* Annual of Scientific Discovery, 1866-7, p. 267. Proc. Bos. Soc. Nat. Hist, 
1866. At the recent meeting of the American Association, Prof. Wurtz ("| 
that the Colorado bitumens resembled Albertite; they are not therefore allied 
the California asphalts. ' 
+ For authorities, see papers before quoted. 
