Sioux City Academy of Science and Letters. 135, 
GEOLOGY OF DAKOTA COUNTY, NEBRASKA, 
WITH SPECIAL REFERENCE TO THE 
LIGNITE DEPOSITS. 
BY ERNEST F. BURCHARD. 
INTRODUCTION. 
A study of the areal and economic geology of Dakota 
County, Nebraska, was made by the writer in the field 
and laboratory during the Spring and Fall of 1902. A 
topographic map of the county was made on a scale of 2 
miles to the inch with 100-foot contour interval (fig. 1), 
also a topographic map of one of the lignite areas on a 
scale of 8 cm. to the mile with 20-foot contour interval 
(fig. 2), and the geology was mapped directly on these 
bases. Prior to this work no geologic mapping had been 
done immediately to the west of Missouri River in this 
vicinity, although many geologists had visited the region 
and were familiar with its general geologic relations. 
The distinct objects borne in mind in this work were: 
To study the physiographic features, and the relation of 
the rocks of the west side of Missouri River Valley to 
those of the east side; to determine if possible, whether 
Tertiary deposits are present this far east on the Great 
Plains; and to investigate thoroughly the lignite depos- 
its. 
Dakota County, Nebr., is situated at the extreme 
northeast corner of the State, where Missouri River bends 
from a southeast to a more southerly course, and oppo- 
site the mouth of Big Sioux River. At this junction the 
states of Iowa, Nebraska, and South Dakota border on 
one another. The greatest length of the county from 
north to south is 24 miles and from east to west is 19 
miles. Its area is about 290 square miles. The proxim- 
