STRATIGRAPHIC POSITION OF JUDITH RIVER FORMATION 641 
FEET 
Variable bed, consisting of alternations of sand and clay, with 
large concretions, with species of Melania, Paludina, Helix, 
Planorbis, Cyclas, Iguanodon, and Megalosaurus......... 100 
Alternations of impure lignite and yellowish-brown clay with 
Unio, Paludina, Melania, Cyclas, and Lepidotus......... 25 
Ferruginous sand and clay, having in the upper part a seam 3 
or 4 inches in thickness composed mostly of shells of Unio. 
Lower part ferruginous and coarse gray grit with a seam 
near the base entirely composed of remains of Unio Danai, 
U.. Deweyanus, and U. subspatulatus.......0.5....0...43 100 
FOX HILL’S FORMATION 
Yellowish and reddish, rather coarse-grained sandstone, 
becoming deep red on exposure with Inoceramus ventricosus, 
Mactra alia, and Cardium spectosum....:..:....--2.2.+-: 20-25 
Mixed pure and impure lignite—whole bed containing many 
crystals of selenite and a yellowish substance like sulphur. 
The masses of lignite when broken reveal in considerable 
quantities small reddish crystalline fragments of a sub- 
stance having the taste and appearance of rosin 
Variable strata of drab clay, and gray sand and sandstone. 
Near the middle there are gray or ash-colored clays with 
very hard bluish-gray granular siliceous concertions with 
Ostrea glabra, Hetangia americana, Panopea occidentalis, 
LINAWMVACEIN GA ONMOS Caden eee at Hn. Sune SANs 80-100 
The table given on p. 642 gives the list of species collected by 
Hayden in the beds [Fox Hills] underlying the Judith River beds 
as identified by Professor F. B. Meek,’ together with their outside 
distribution in other parts of Montana, the Dakotas, and Colorado. 
In the last column is shown the recurrence of these species in Stan- 
ton’s Claggett formation, which apparently occupies the same posi- 
tion in relation to the Judith River beds, including without doubt 
the beds shown in Hayden’s section, which are identical with the 
sandstones found by the writer at the top of the dark Pierre shales 
and below the lighter-colored clays, sands, and shales of Judith 
River age. In these lower sandstones invertebrate fossils of Fox 
Hills age were found. 
t Report U.S. Geol. Surv. Terr., TX (1876), 1-506. 
