Stoux City Academy of Science and Letters. 169 
‘bury County, and the Greenhorn limestone rests directly 
-on the Dakota, we have an explanation which admits of 
correlating these lignites with those of the northern part 
of the county. In Woodbury County at Sargent’s Bluffs, 
across the river and a little north of the Homer locality 
is an exposure of Dakota sandstone containing a bed of 
somewhat earthy lignite, 14 feet thick. The writer con- 
siders that this bed is probably the equivalent of that 
outcropping in the Homer locality. 
Conditions more favorable to the origin and develop- 
ment of a bed of lignite prevailed during the deposition 
of the Dakota beds, these rocks being characterized by 
‘the scarcity of remains of marine life, and by the abund- 
ance of impressions of fragments of wood and of leaves 
belonging to species of plants resembling our modern 
forest trees. Low swamps probably bordered the shore, 
delimited by higher land to the east and by deeper waters 
‘to the west. 
With the subsidence and burial of such beds of vege- 
tation through deepening of the sea during Benton times 
organic material, logs and drift wood such as might 
accumulate in estuaries of the sea would provide mate- 
yial for the formation of lignite deposits, and to such 
‘conditions may be ascribed the formation of the bed near 
Ponca and its fragments in Dakota County. 
Physical properties—During the period of prospect- 
‘ing the Goodfellow tract by use of the churn drill but lit- 
tle satisfactory information as to the physical character 
-of the lignite could be obtained. It was impossible, 
although the drill holes were cased from the surface 
down nearly to the bottom of the hole, to keep the sand 
and loose wail material from mixing with the drillings 
from whatever stratum the drill was penetrating, and 
washing up with them in the sluice. 
Chemical analyses made upon such drillings separ- 
ated from most of the accompanying foreign material, 
and subsequently upon the lignite from the same bed, in 
lumps from the shaft, show approximate identity of com- 
position, so that such analyses made of drillings can be 
considered reliable data in so far as indicating the proxi- 
‘mate constituents of the material. As to the uniformitv 
-of the material in the bed, whether containing clay or 
