STRATIGRAPHIC POSITION OF JUDITH RIVER FORMATION 537 
the marine and fresh-water beds, though no fossils excepting silicified wood 
were found in the lower 200 feet of the latter. The remainder of the section, 
about 300 feet in thickness, is apparently conformable with the underlying 
beds, but is quite distinct from them in color and texture. It consists of 
alternations of light-colored, soft, friable sandstones, clays, and marls, with 
some seams of lignite and purplish carbonaceous bands. Fossils are abundant 
in the upper 200 feet, consisting of fragments of silicified wood, bones, and 
numerous invertebrates. The latter include the following species: 
Sphaerium recticardinale Goniobasis sublaevis 
Sphaerium planum Goniobasis subtortuosa 
Unio danae Goniobasis sp. closely related 
Unio cryptorhynchus to G. tenuicarinata 
Anodonta propatoris Campeloma vetula 
Viviparus conradi Vetrina ? obliqua 
Helix veternus Physa copei 
At the top of the exposure above these fresh-water beds there is a band of 
brackish-water fossils, reported by both Meek and Hayden and by Cope, 
which contain Ostrea subtrigonalis, Anomia sp., Corbicula occidentalis, Corbula 
cytheriformis, Goniobasis convexa, etc. This band was not seen by me in the 
neighborhood of Judith River, but I afterward saw it near Havre, Mont., 
holding the same position above the fresh-water beds. 
Cross, in commenting on this section, refers to the specific 
identity of the brackish-water shells found by Stanton on Dog 
Creek and near Havre with those found by Weed in the Living- 
ston’ beds, saying their presence does not indicate the Laramie (by 
which he means true Laramie as found in Colorado) age of the 
Judith River beds, and as to the apparent conformity with the 
Fox Hills urges for the Judith River beds the.same considerations 
as he did in discussing the Converse County beds (now called the 
Lance) in Wyoming. These as given on p. 236 are as follows: 
There are many places in the West where the section of visible sedimentary 
formations from the Cambrian to the Cretaceous seems a conformable one, and 
‘it has frequently been spoken of as such, but the researches of the last two 
decades have proven the existence of many important stratigraphic breaks 
in this series, which are in certain places shown as great unconformities but 
cannot be identified at other points. Especially in the plains country adjacent 
to the Rocky Mountains conformity of formations cannot be assumed to prove 
continuity of sedimentation. The visible conformity between the Ceratops 
The Livingston age of these beds was afterward denied by Dr. Stanton and 
others, but the point the writer wishes to make here relates more especially to the 
unconformity. 
