ON THE STRATIGRAPHIC POSITION AND AGE OF THE 
JUDITH RIVER FORMATION 
A. C. PEALE 
PART II 
THE STRATIGRAPHIC POSITION 
Hayden, who was the first to note and study geologically the 
Judith River beds, and to whom the name is due, gives the first 
published section of them as he found them in the type region near 
the mouth of the Judith River, following it with a section of the 
marine strata (Fox Hills) immediately underlying them. Com- 
bining these two sections into one we have the following" 
HAYDEN’S SECTION OF JUDITH RIVER BEpDs? 
“Section of fresh water and estuary deposits at the mouth of the Judith River” 
JUDITH RIVER FORMATION 
TOP 
FEET 
Yellow arenaceous marl passing downward into gray grit, 
with seams of impure lignite with Ostrea subtrigonalis, Cyrena 
occidentalis, Melania convexa, and Paludina Conradi...... 80 
Impure lignite, containing much sand with Ostrea.......... 10 
Alternations of sand and clay with particles of lignite; also 
reddish argillaceous concretions with a few saurian teeth 
andi iresh=waterShells cismestesver. me vce e a arate an enaees reeves 80 
Alternate strata of sand and clay, with impure lignite and sili- 
cified wood, in a good state of preservation.............. 20 
t Trans. Amer. Phil. Soc., 11, N.S., Philadelphia, 1860, pp. 129, 130. 
2 Hayden, according to his habit, constructed his general section from ‘‘a large 
number of local sections” ‘‘taken at different points.” This is the only section of 
these beds ever published by him. The type locality is shown on the map (PI. 8) 
opposite p. 154, in the area marked “‘B. L. (Badlands of the Judith) ” overlooking the 
mouth of the Judith River, and is the only locality on the map so marked along the 
entire course of the Judith River. Hence it must be considered the tyfe locality. 
Professor F. B. Meek says that the Judith River Group was “first examined by him 
[Dr. F. V. Hayden] at the typical locality near the mouth of the Judith River on the 
upper Missouri River in Montana.”—U.S. Geol. Surv. Terr., 1X, p. xlvii. 
640 
