326 ASS1NNIB0INE AND SASKATCHEWAN EXPEDITION. 



dip of the strata, from beneath the northern portion ot 

 the Great Lignite Basin, as will be seen by reference to 

 the section on the map. Near the mouth of the Mussel 

 Shell Eiver it occupies the whole country for a distance 

 of about eighty miles, and thins out upon the tops of the 

 hills near the mouth of the Judith Eiver. 



In summing up the extent of country underlaid by 

 this great formation, we find that south of the Lignite 

 Basin, it occupies an area of 200 miles in length and 

 100 in breadth, or 20,000 square miles. North of the 

 Great Lignite Basin, commencing at its first appearance 

 near Milk Eiver, we find it covering an area of 200 miles 

 in length and 60 in breadth, or about 12,000 square 

 miles. I have been thus particular in estimating its 

 approximate limits and extent of surface on account of its 

 influence on the future destiny of that region. Wherever 

 this deposit prevails, it renders the country more com- 

 pletely sterile than any other geological formation I 

 have seen in the north-west. We see from the above 

 estimate that it renders barren over 30,000 square miles 

 of the valley of the Missouri. 



The fossils of this formation are too numerous to men- 

 tion in detail. The upper and lower members appear 

 to be exceedingly fossiliferous, while the intervening 

 portions of considerable thickness contain only a few 

 imperfect specimens of Cephalopoda and the bones of 

 Mosasaurus Missouriensis. The entire thickness of this 

 formation may be estimated at about 350 feet.] 



The formation is probably more extensively developed 

 in Eupert's Land than any other member of the Creta- 

 ceous Series. 



The most easterly exposure, where it holds character- 

 istic fossils, is on the Little Souris. Fifteen miles from 

 the mouth of that river it consists of a very fissile, dark- 



