REPORT OF A RECONNAISSANCE OF JUDITH BASIN, AND OF A TRIP 
FROM CARROLL TO FORT ELLIS, VIA YELLOWSTONE RIVER. 
By Lirvut. R. E. THompson. 
Fort STEVENSON, DaAk., March 8, 1876. 
Sim: I have the honor to forward herewith a report of the reconnaissance of the Judith Basin, 
made during the past summer, in accordance with your orders, and an account of my subsequent 
return from Carroll, Mont., to Fort Ellis, by way of the Yellowstone River. 
The trip to the Judith River, which was laid out as part of the summer’s work, on condition 
that it could be completed before the close of navigation on the Upper Missouri, was ordered from 
the camp on Armell’s Creek, September 11. Its object was the examination of the country in the 
vicinity of the Judith, with regard to its topographical features, to accurately locate its position, 
but more particularly to afford an opportunity for a thorough search for fossil remains in the cut 
banks of its valley, which offer so extensive an exposure. The party consisted of a sergeant and 
one private of the Engineer Battalion, charged with running the trail by compass and odometer; a 
detachment of a sergeant and seven privates of the Second Cavalry as escort; and Reynolds as 
guide. 
Mr. G. B. Grinnell and Mr. Ludlow accompanied the party; the former interested in the 
paleontology and zoology of the country. Sextant-observations were made by Mr. W. H. Wood 
whenever practicable. 
Including myself, the party numbered fifteen men, all mounted, save the teamster, the ser- 
geant in charge of the odometer-cart, and the man charged with the care of the chronometers. 
On the morning of September 12, the party was put en route across a stretch of rolling prairie 
country. The general course was toward Square Butte, a landmark in the vicinity of Benton, 
considerably west of the point to be reached ; but it:was deemed advisable, from lack of knowledge 
of the country, and from the broken appearance to our right, to make the divide between Dog 
Creek and the Judith, and to follow this up till opportunity offered to descend to the valley of the 
latter stream near its mouth. The headwaters of Dog Creek were reached in the afternoon. Here 
I was joined by Reed, who had volunteered his services as guide. Camped ata pool near this 
creek. 
In the morning (September 13), a course more to the north was taken, bearing nearly on Bear’s 
Paw Mountains. The divide was kept from necessity, either valley being impassable for wagon. 
Shortly after leaving camp, the broken character of the Judith Bad Lands began to appear to our 
left and front. 
For twenty miles back from the mouth of the stream, the country immediately tributary to it 
is washed and cut into the wildest and most rugged shapes. The soil is of that clayey character 
capable of supporting itself at steep inclines; and where ordinarily the drainage would be con- 
ducted in simple valleys or natural depressions, here gulches and ravines, with precipitous sides, 
are formed by the flow of the water. The worst of these were avoided, and to within ten miles of 
the mouth of the Judith our path was over a country such that a heavily-loaded wagon-train could 
have been conducted with but little difficulty. 
