8 UNITED STATES GEOLOGICAL SURVEY— TERTIARY FLORA. 



ical circumstances influencing the character of the countries surveyed, all have 

 been considered and studied by Hayden. His researches show tlie constant 

 vigilance and circumspection of a master attending to the performance of a 

 great work, the building of a monument whose plan has l)een prepared by 

 serious scientific studies. I speak here by experience, for in the part assigned 

 to me I had to follow, so to say, the footsteps of the master, and found that 

 even the matters of the least importance had been already recorded by him, 

 and outside of my specialty, the study of the paleobotany of the Cretaceous 

 and the Lignitic, I could scarcely find anything worth mentioning as new. 



The first explorations of Dr. Hayden over the western coal regions, to 

 which the name of Great Lignitic is generally and appropriately given, were 

 extended first up the Missouri River from the first appearance of the Tertiary 

 strata near Fort Clarke to the mouth of the Yellowstone, and thence up that 

 river to a point near the mouth of the Big Horn for a distance of about six 

 hundred miles. He considers that the area of the Lignitic formations cannot 

 be, on the Upper Missouri, less than one hundred thousand square miles, 

 without taking into account the belt which extends far north across the 

 boundary of the United States into the British Possessions.* 



On the geological map of the Yellowstone and the Missouri Rivers, 

 prepared for the explorations of Capt. W. Raynolds and Lieut. H. E. Mayna- 

 dier for 1859-60, the part colored as Tertiary Lignitic by Dr. Hayden, who 

 had charge of the geological researches, indicates a wider area, not less than 

 one hundred and twenty-five thousand square miles, and this only from the 

 boundary of the British Provinces to the Black Hills. Between these and 

 the Rocky Mountains, south to the Nebraska River, the Tertiary belt is still 

 continued over a surface of about sixteen to seventeen thousand square miles. 

 Farther south we have not as yet any map exposing the distribution of the 

 Tertiary. Prof Hayden, considering this part of the area occupied by the 

 Lignitic, says:t — "We may trace it southward in a broad continuous belt across 

 the Yellowstone River, between the Black Hills and the Big Horn Mountains, 

 until it is overlapped by the White River group about sixty miles north of 

 Fort Laramie. If we continue southward along the base of the Laramie 

 Range, we find that the Lignitic group reappears about ten miles south of the 

 Union Pacific Railroad ; that where the White River group and the Lignitic 



' Report of the United States Geological and Geographical Survey of the Territories, 1874, p. 20. 

 t Loc. cit., p. 2G. 



