124 
GEOLOGICAL SKETCH OF THE ESTUARY AND FRESH WATER DEPOSIT 
That portion of the “ Bad Lands ” which is formed of the estuary deposit under considera¬ 
tion, lies between these two streams. About thirty miles north of the entrance of the 
Judith River into the Missouri, is the Bear’s Paw Mountain, a small range, the highest 
peak of which is elevated about 2000 feet. On the same side of the Missouri, and in 
nearly a north-easterly direction, are the Little Rocky Mountains; a range similar to the 
Bear’s Paw, though apparently disconnected from it. On the south side of the Missouri, 
about fifteen miles south-west of the mouth of the Judith, the Square Buttes may be seen 
rising 400 or -’00 feet above the surrounding prairie, and are the nearest upheaval of trap- 
pean rocks to the Missouri in this region. From thirty to fifty miles south, is quite an 
extensive range, called the Judith Mountains, which have not yet been explored geologi¬ 
cally. Here comparatively small local upheavals seem to' represent the dying out of the 
intense subterranean forces which uplifted the vast Rocky Mountain chain. It will be 
important to understand the geographical position of these mountains in order to fully 
appreciate the sources of the power which has disturbed the strata of the more recent 
fossiliferous rocks, a point which will be again referred to in this paper. 
Lewis and Clarke in their interesting account of an expedition to the sources of the 
Missouri, give a brief but accurate description of the physical features of this remarkable 
region, but dwell more in detail on the picturesque portions near the “ Stone Walls,” which 
are composed of the basis strata upon which the estuary deposits of the “Bad Lands” of 
the Judith rest, which are doubtless of the age of Cretaceous Formation No. 1, or Upper 
Jurassic. The Prince of Neuwied also notices this unique scenery, and in his folio atlas 
of Plates are some beautiful delineations of the external features of the country.* 
On page 228, he says:—“ Near Lewis and Clarke’s Big Horn Island, we again saw most 
singular summits on the hills. Entire rows of extraordinary forms joined each other, and 
in the lateral valleys we had interesting glimpses of this remarkable scenery, as we were 
now approaching the most interesting part of the Mauvaises Terres. I have already de¬ 
scribed these mountains when speaking of the White Castles, but here they begin to be 
more continuous, with rough tops, isolated pillars, having flat slabs or balls, resembling 
mountain castles, fortresses, and the like, and they are more steep and naked at every 
step. Often one may plainly perceive hills or mountains that have evidently sunk into 
the marshy valley. Many strata are inclined at an angle of 30° to 60°, and others per¬ 
fectly horizontal. The course of the Missouri among these mountains is pretty strait, 
only narrow plains or prairies covered with artemisia arid the prickly bushes of the pulpy 
thorn, lie on its banks before the mountains, which frequently come very near the river, 
with large blocks of sandstone at their foot, between which fragments of selenite are seen. 
* Travels in the interior of North America: By Maximilian, Prince of Wied, with a folio atlas of eighty-one 
plates. English Edition. 
