LOWER CRETACEOUS FORMATIONS AND FAUNAS 593 
have been reported from these southern beds. According to 
Mr. N. H. Darton’ the Potomac deposits are practically contin- 
uous along the whole Atlantic coastal plain until they connect 
with the Tuscaloosa. It is evident that conditions of deposition 
were remarkably uniform throughout this long coastal border 
region during Potomac time but the earlier part of the epoch is 
recorded by deposits now visible only in the middle portion of 
the area. The northern and southern ends either did not receive 
deposits until towards the close of the epoch or else the early 
deposits were overlapped and concealed by the later beds. 
The Kootanie formation.— A somewhat detailed description of 
the typical area of the Kootanie is given by Dr. Geo. M. Dawson.? 
It is found in the Rocky Mountains of Canada between latitudes 
49° and 51°30’. 
of over 7000 feet and consist chiefly of shales and sandstones of 
The beds there havea total estimated thickness 
very varied texture and appearance, with beds of coal. The 
Canadian localities have yielded a flora3 of about 27 species 
which show by identical and allied species a very close relation- 
ship with the Potomac. No animal remains have been reported 
excepting one imperfect specimen of a Goniobasis indicating 
fresh waters, and a fragment of a belemnite which was very 
probably derived from an older formation. 
In the United States the Kootanie occurs at Great Falls, Mon- 
tana, near which place a thick coal bed in the formation is mined. 
The section has been described by Mr. W. H. Weed‘ who states 
that the Kootanie ‘is a series of rapidly alternating sandstones 
and clay shales with few and thin beds of impure limestone. 
Individual beds are inconstant, the heavy ledges of heavy sand- 
stone passing laterally into arenaceous clays and vice versa.” 
The top of the formation is not clearly defined but the thick- 
ness is evidently several hundred feet. About 38 species of fossil 
* Bull. Geol., Soc. Am., Vol. VII, 1896, pp. 514-517. 
?Rept. Geol. Surv. of Canada for 1885, Rept. B. A more general account in 
Am. Jour. Sci., 3d ser., Vol. XX XVIII, pp. 120-127. 
3Trans. Roy. Soc. Canada, Vol. III, 1885, Sec. 4, pp. 1-10. Idem, Vol. X, 1892, 
SCA PO OS mee lGem- a VOlm Nl TSO2s SEG. Anise 
4Two Montana coal fields. Bull. Geol. Soc. Am., Vol. III, 1892, pp. 301-323. 
