THE LARAMIE AND FORT UNION BEDS IN NORTH 



DAKOTA. 



While considering economic problems in North Dakota and 

 eastern Montana, abundant opportunity was given to examine the 

 beds that in geological literature have long been known as the Fort 

 Union, and to compare them with beds that have been assigned 

 without -question to the Laramie. From this study certain definite 

 impressions were gained in regard to the relationship existing between 

 the Fort Union beds and the Laramie. In stating these impressions, no 

 effort will be made to contribute to the already abundant literature 

 bearing on the larger question of the position of the Laramie as a whole. 



The field w^ork covered six months in the years 1902 and 1903, 

 the area studied including the entire western half of North Dakota 

 and eastern Montana along the Yellowstone. The unusual exposures 

 along the Missouri throughout the three hundred miles of its course 

 in North Dakota were examined, the trip down the river being made 

 by boat. From the western boundary of North Dakota the river 

 passes from beds that have been regarded as typical Fort Union, to 

 an area that has been assigned without reserve to the Laramie. The 

 tributaries of the Missouri from the west and the bad lands also give 

 abundant opportunity for stratigraphic study. 



Though eager to discover vertebrate remains, none were found, 

 except great numbers of buffalo bones in the lower river terraces. 

 MoUuscan and plant fossils, however, were collected at a number of 

 points. The molluscs w^ere identified by Mr. T. W. Stanton, and 

 the plants by Mr. F. H. Knowlton, of the U. S. Geological Survey, and 

 those that seem to be suggestive in considering the relation of the 

 Fort Union to the Laramie will be noted. 



The area supposed to be occupied by the Fort Union beds 'has 



never been definitely outlined. Lesquereaux^ states that they occupy 



the whole country about Fort Union, extending north into the British possessions 

 to unknown distances; also southward to Fort Clarke; seen under the White 

 River group, on Noith Platte River, above Fort Laramie; also on west side of 

 Wind River Mountains. 



I United States Geological Survey, Vol. VII, p. 24. 



290 



