132 
GEOLOGICAL SKETCH OF TOE ESTUARY AND FRESH WATER DEPOSIT 
a horizontal to a vertical position. It is also evident that the convulsion was synchronous 
with that which uplifted the surrounding Cretaceous strata of No. 1, and that the moun¬ 
tains in the vicinity were raised up by the same forces that elevated the Black Hills, La¬ 
ramie Mountains, &c. These facts strengthen the opinion that the deposits of the Judith 
basin, if not an American representation of the Wealden of Europe, are, at least in part, 
as old as Cretaceous. 
Table Showing the Stmt (graphical Position of the Fossils from the Bad Lands of the Judith. 
VERTEBRATA. 
Palseoscincus costatus, Leidy. 
Trachodon mirabilis , 
Troodonformosus, 
Deinodon horridus, 
Crocodilus humilis, 
Trionyx foveatus, 
Lepidotus occidentalis, 
Lepidotus Iluyden i, 
A B C D E F G 
MOLLUSCA. 
Cyrena occidentalis, 
Corbula subtrigonalis, 
Corbula perundata, 
Physa subelongata, 
Paludina vetula, 
Paludina Conradi, 
Melania subtortuosa, 
Melania omitta, 
Melania subloevis, 
Melania invenusta, 
Yitrina obliqua, 
Helix occidentalis, 
Helix vitrinoides, 
Planorbis tenuivolvis, 
Planorbis amplexus, 
Uuio Hanai, 
Unio Deweyanus, 
Unio subspatulatus, 
Meek and Hayden 
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i 
1 
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The remains described by Dr. Leidy in this Memoir from the Great Lignite Basin, w r ere 
obtained from the lower beds, which partake somewhat of an estuary nature. In order 
that the lithological characters of this deposit may be understood and comparisons made 
with the other deposits of a somewhat similar character, I have added a section of the 
strata, mostly constructed from a local section taken about ten miles above Fort Clarke 
on the Missouri River. A few localities showing the geographical distribution of the beds 
which occur at this point, are also given, but it is impossible with the materials in our pos- 
