FEBRUARY i5, 1901.] 
were reviewed. It was shown that a gap ex- 
isted between the known localities in northern 
Nevada and California on one hand, and those 
of British Columbia on the other. This gap 
has partly been bridged by the discovery of an 
extensive series of marine Trias in northeastern 
Oregon. No Trias has previously been found 
in this State. 
The, result of a reconnoissance during the 
past field season has shown that the larger part of 
the Blue Mountains of Oregon are made up of 
older rocks of probably Carboniferous age. In 
the Hagle Creek Mountains, however, which 
form a circular mountain group in the extreme 
northeastern corner of Oregon, surrounded on 
nearly all sides by Columbia River lava, the 
marine Trias was found very strongly devel- 
oped, although the fossils thus far obtained do 
not ‘afford paleontological subdivisions. The 
fossils, though scant, unquestionably indicate a 
Triassic age. They consist, besides pentacrinus 
stems and fragments of echinoids and ammo- 
nites, of various specifically indeterminable 
Halobias and Danonellas. The series consists 
of a great thickness, probably several thousand 
feet of shales and limestones. Associated and 
interbedded with these are vast masses of tuffs 
and various old lavas. The limestone is very 
prominently developed and its weathering gives 
rise to peaks and cliffs of Alpine character. 
The same series was found well represented 
in the Snake River canyon on the boundary of 
Idaho and Oregon. Here, however, the vol- 
canic material predominates, the sedimentary 
rocks appearing as intercalated masses. Halo- 
bias were again found inthis series. It appears 
that these Triassic rocks continue with a north- 
easterly strike into Idaho across the Seven 
Devils and the lower Salmon River Canyon, 
until at some point in the vicinity of the Clear 
Water River, they give place to intrusive 
granites and older schists. 
A Comparison of the Ouachita and Arbuckle Moun- 
tain Sections, Indian Territory: J. A. TAFF. 
The Ouchita mountain range extends from 
the vicinity of Little Rock, Arkansas, to the 
Missouri, Kansas and Texas Railway, near 
Atoka, in Indian Territory. The hard sand- 
stone and novaculite formations make ridges 
SCIENCE. 
271 
rising from 1,000 feet at the end of the range, 
to nearly 2,000 feet in the central part. The 
high ridges have strikingly level crests which 
probably represent a Cretaceous plain. The 
softer rocks are generally worn down to heights 
between 600 and 1,000 feet above the sea. 
The Arbuckle range, with the exception of a 
central igneous peak, contrasts strongly with 
the Ouachita range in physiographic aspects. It 
is strictly a plateau, only partially dissected and 
but little below the original Cretaceous base 
level. It rises gradually to about 1,350 feet on 
the west, from the Cretaceous contact having an 
average elevation of 750 feet, on the east and 
southeast. The gap between the Ouachita and 
Arbuckle uplifts is about 20 miles wide and 
is occupied by slightly disturbed coal measures 
and Cretaceous rocks. 
The lowest rocks in the section of the Ouachita 
range are Lower Silurian sediments in the heart 
of the uplift near the Tertiary border southwest 
of Little Rock. Above these are the Lower Si- 
lurian novaculites, 1,200 feet thick, which were 
the highest Silurian strata recognized by L. 8. 
Griswold, of the Arkansas Geological Survey. 
In Indian Territory above the novaculites are 
about 5,000 feet of shale. These are in turn 
succeeded by about 5,000 feet of sandstone. 
Above these sandstones comes limestone of 
Ordovician age. Lower Helderberg cherts and 
limestone, Mississippian shales and coal meas- 
ures, complete the section above the Ordo- 
vician. 
The section of the rocks in the Arbuckle 
mountain uplift from the Lower Helderberg 
upward is a repetition of the Ouachita moun- 
tain section upward from the same terrane, but 
is not nearly so thick. Below the lower Helder- 
berg is a mass of Ordovician limestone with 
shale and sandstone of minor importance, reach- 
ing a total thickness of more than 6,500 feet. 
These cannot be compared lithologically with 
the known Ordovician in the Ouachita mountain 
uplift. The limestones rest uncomformably 
upon a mass of older granites with a variable 
intervening bed of arkose and conglomerate. 
The structure of the Ouachita range is typ- 
ically Appalachian. The rocks for the most 
part have been sharply folded and very exten- 
sively overthrust. The structure of the eastern 
