No. l.] HOLMES ON FOSSIL FORESTS OF YELLOWSTONE PARK. 129 
Laurus canariensis , 
Tilia (new sp.), 
Fraxinus (new sp.), 
JDiospyros (new sp.), 
Cornus (new sp.), 
Fteris (new sp.), 
Alnus (new sp.), and a 
Fern (new sp.). 
It will be observed that most of these species are new, which was also 
the case with the collection of Professor Whitney. It is also worthy of 
remark that none of the genera are identical with those of the Elk 
Creek locality previously mentioned. The stratigraphical relations of 
the two localities cannot easily be made out, as they are separated by 
fifteen m iles of broken country in which the strata are obscured by igne- 
ous flows and Quaternary drift. The Elk Creek strata are lower by fully 
one thousand feet. 
As far above the leaf-bearing horizon as I was able to ascend, the sili- 
cified trunks were very numerous and well preserved, and, by the aid of 
a field-glass, others could be detected in all parts of the cliff to the 
highest stratum. 
At another point, nearly a mile farther east, I climbed the rugged 
walls of the mountain for the purpose of examining a number of large 
trees that were visible from below. Trunks and fragments of trunks 
were found in great numbers and in all conceivable positions. In most 
cases the woody structure is well preserved, the trunks have a tendency 
to break in sections, and on the exposed ends the lines of growth, from 
center to circumference, can be counted with ease. In many cases the 
wood is quite completely opalized or agatized, and such cavities as ex- 
isted ip the decayed trunks are filled with beautiful crystals of quartz 
and calcite. Our party was so fortunate as to procure some very hand- 
some specimens of amethyst and ferruginous quartz. It is a matter 
worthy of observation that nearly all of the beautiful crystals that occur 
so xfientifully in this region have been formed in the hollows of silicified 
trees. The same fact has been noticed in regard to similar crystals in 
many parts of the West, and notably in the case of the smoky quartz of 
the Pike’s Peak region in Colorado. 
The silicifying agents have been so unusually active in the strata of 
the Volcanic Tertiary that not only are all organic remains thoroughly 
silicified, but all cavities in the loosely bedded rocks and all fracture- 
lines in the strata are filled with chalcedony or other forms of quartz. 
On reaching the heavily bedded conglomerates of the upper third of 
the cliff, I found the trees still more perfectly preserved. Many of the 
trunks are twenty and thirty feet in height. Their roots are in most 
cases imbedded in the layers of finer-grained materials, in which they 
grew, while the battered and branchless trunks are encased in the coarse 
conglomerates and breccias. These latter rocks are composed chiefly of 
Bull, v, 1— — 9 
