Cretaceous Mocks of Iowa. — Calvin. 303 
line farther up the Missouri, the chalky beds of the Niobrara 
group crop out on all the higher hill tops. The village of St. 
James is situated in the valley of Bow creek, below the level of 
the chalk. In the eastern edge of the village is an exposure of 
Fort Benton shales, presenting the same characteristics as seen 
at a recent landslide on the farm of Williams and Smith, a few 
miles north of Sioux City in Iowa, and at the exposures near 
Ponca, Nebraska, This shale furnished a very perfect skeleton 
of a saurian, as it was penetrated in digging a cistern on Sec. 35, 
T. 90, R. 47, on the Iowa side of the Big Sioux. Another simi- 
lar skeleton, that was carried about the country some years ago 
for exhibition purposes, was taken from the same horizon near 
Ponca. A few weeks before my visit a portion of a skeleton, 
forty feet in length, was uncovered in excavating in the Fort Benton 
shales near St. James. On the tops of the hills near the mouth 
of Bow creek the dark Fort Benton shales are succeeded by the 
white or cream-colored chalk of the Niobrara division. 
St. Helena, about eight or nine miles above St. James, is situ- 
ated on a high bluff 130 or 140 feet above the level of the Mis- 
souri river. The bluff rises as a vertical wall almost from the 
edge of the water. Between the river and the vertical escarpment 
the base of the bluff is concealed by a talus composed chiefly of 
great blocks of chalk; but above the talus, and rising to a hight 
of forty feet above the water, is an excellent exposure of the 
dark shales of the Fort Benton group, differing in no essential 
respect from the corresponding shales exposed at the land slide 
above the creamery of Williams and Smith, or the shales occupy- 
ing the same stratigraphical position near Ponca and St. James. 
Above the Fort Benton shales lie 90 feet of soft chalk belonging- 
to the Niobrara. The Niobrara beds at St. Helena exhibit some 
points of difference from those seen on the Big Sioux or on the 
Missouri across the valley in Nebraska. The valves of Inoceramus 
are no longer present in such numbers, but some of the layers are 
crowded with Ostrea congesta. One impression of the peculiarly 
corrugated muscular scar of Haploscapha grandis was noticed. 
The beds are uniformly chalky throughout, no part of the deposit 
being as much indurated as the /noceramws-bearing beds near 
Ponca or Sioux Cit}-. The exposure at St. Helena is probabl}' 
one of the most striking and interesting along the river and Hay- 
den refers to it time and again in the work already cited. 
