GEOLOGY AND PALEONTOLOGY. Trav. 
tude of Lincoln. This would indicate that the thickness of the Dakota in this 
locality is between 350 and 400 feet, which agrees well with the thickness in 
other localities. A recent publication by Mr. N. H. Darton, of the United States 
Geological Survey, gives a much more comprehensive report of the Lancaster 
county outcrops.* 
The Platte Locality.—This is the only locality in the Nebraska area where 
the nonconformity between the Carboniferous and the Dakota maybe seen. The 
outcrops occur on both sides of the Platte river, from Plattsmouth to Fremont, a 
distance of fifty miles. The fact of the extreme irregularity of pre-Cretaceous 
erosion is here well exemplified. One of many examples may be cited on the 
north side of the river, nearly opposite Louisville, where two instances of non- 
conformity, not more than a quarter of a mile apart, differ eighty feet in altitude. 
The numerous limestone quarries along the river usually exhibit more or less 
of the Dakota between the Carboniferous below and the glacial above. In this 
case there are of course two nonconformities: the first between the Carbonifer- 
ous and Dakota, and the second between the Dakota and the drift. Often the 
lines of the two non-conformities are but a foot or two apart, indicating that 
during preglacial time the sandstone was almost entirely removed by erosion. 
In other places the Dakota has all disappeared and the drift rests directly upon 
the unevenly eroded Carboniferous limestone. Again, the sandstone forms high 
cliffs, as at the Santee caves, opposite Ashland. The most westerly exposure 
known in the locality is a small outcrop in the bluff where the west road leaves 
. the river, two miles south of Fremont. 
The Missouri Locality.x—From Omaha to Ponca is 120 miles. Between 
these two places, along the bluffs on the west bank of the Missouri river, the 
Dakota is exposed almost constantly. In places the mantle of loess covers the 
sandstone to the depth of several feet, and the latter may not be exposed for 
miles. Usually, however, the more or less conspicuous outcrops may be seen 
half way up the slope. Not infrequently the presence of springs issuing from 
the loess indicate that the water-bearing Dakota lies just beneath the surface. 
In the northern part of the locality, near Homer, Jackson, and Ponca, the 
upper part of the bluffs are composed of Benton limestone. At the High banks, 
a mile north of Decatur, at Blackbird hill, and at the old mission, the Missouri 
washes cliffs of Dakotasandstone. It wasthese bluffs standing boldly out into the 
river that caught the attention of the early explorers. Much historical interest 
attaches to these places. This is not only the type locality of the Dakota, but is 
also the region concerning which the early controversy waged, and the place 
where the question was finally settled. 
Big Sioux Locality.— Under this head are included the exposures east of 
the Missouri river, near Sioux City, Iowa. At Riverside park, on the east bank 
of the Big Sioux river, a mile from its mouth and three miles from Sioux City, 
the following section was taken illustrating the position of the beds: 
ING: G,. Liosasegeey ee 28 tee ote LC OO ICO are Se 10-100 feet. 
Deis: cise PELE tile ere terete erie te cro ie ale aie Sheree: wad Biase 
No. 4. Thin limestones and shales, Benton............. ae allay 
No. 3. Yellow, blue and gray shales and clays, containing 
shoellstandiconeretionsien 261. sate ble eis GOP act 
No. 2. Heavy ledge of sandstone containing leaves ..... Lay tt 
INO 1) Slope tromipmiol SOU VOD tis elses, o/e1e wale amlelelare 205.8 
No. 2 is quarried for building stone and from No. 3 clay is obtained for sev- 
eral brick and tile works. The exposures of both Dakota and Benton are said to 
45. Water Sup. and Irriga. Papers, U. 8. Geo]. Surv., No. 12, pp. 16-19. 
