THE DAKOTA GROUP. 675 
Eh DAKO TAG ROUP! 
BY CHAS. H. STERNBERG. 
In 1853 Dr. Hayden discovered a number of dicotyledonous plants in a red- 
dish and yellowish sandstone in Nebraska. This formation, lying at the base of 
the Cretaceous, he called No. 1, or Dakota Group. Later, in connection with 
Prof. Meek, he discovered the same formation in central Kansas. He found 
that the plants closely resembled living species of the higher types of our forest 
trees. Some of these plants were examined by Dr. Newberry, who found 
among them several genera that were exclusively Cretaceous—and more recent 
collections made by Profs. Mudge, Lesquereux and the writer, have proved con- 
clusively this group to be the lowest in the Cretaceous. On the eastern margin 
this deposit lies on the Permian. The other formations of Mesozoic time have 
been swept away—or, more likely, never existed—and the Permian beds were 
dry land until the opening of the Cretaceous. The rocks of the Dakota Group 
consist of strata of red, yellow and brown sandstone, interlaid with beds of vari- 
ous colored clays and lignite. The sandstone is often found in thin, shaly 
layers. Although the formation has been supposed to be of fresh water origin, 
the recent discovery of marine shells has proved the contrary. The formation 
extends from the Gulf of Mexico through Texas, Kansas and Nebraska; touch- 
ing Iowa, it continues through the British Possessions, and doubtless includes 
‘Greenland and the Arctic lands. In Kansas it is about seventy five miles wide, 
and extends diagonally across the State. Prof. Lesquereux published the first 
description of the flora of this group; and, Jater, his magnificent memoir on the 
' Cretaceous Flora has given us a pretty thorough knowledge of the fossil plants. 
Lesquereux, in addition to his Flora, has published a review of the Cretaceous, in 
which he describes 26 new species, most of which I was fortunate enough to ob- 
tain in the same localities from which he obtained the material for his memoir. I 
think I am correct in saying that I made the first large collection of fossil plants 
from the Dakota. They were sent to the Smithsonian and Dr. Newberry—who, 
so far as I know, has never classified or figured them. They were very fine 
Specimens, and then nearly all were new to science. I showed a number of 
drawings I had made to Prof. Lesquereux in 1872, who said even then a number 
of species were new. Since, from his own and Prof. Mudge’s collections, he has 
obtained all the species represented in my collection—though many of his type 
specimens are much poorer than mine—and I lost the credit due me for my early 
discoveries and science lost the figured representations of some very fine plants. 
I must acknowledge that Prof. Lesquereux mentioned this collection in his Flora 
and gave me full credit for the localities I had discovered and named a number 
of beautiful plants in my honor. One of the earliest plants to excite general in- 
terest was the sassafras; a trilobate leaf with large midribs and well marked 
‘merves. One of the species, S. mudgii, resembles the common sassafras. Nearly 
all the forest trees of to-day are represented in the rich Cretaceous flora. I have 
