92 
BLAIRMORE FAUNA 
The Blairmore formation contains a few freshwater invertebrates, 
which, with the exception of several interesting unios, are poorly pre- 
served. They are listed in the following table: 
Fossil lot No. 
DA4 
CR2 
CR1 
CT1 
Feet below top formation 
310 
1.330 1 
1.330 1 
Hillcrest 
1.620 1 
Feet above base formation 
1,54c 1 
620 
520 
Unio bed 
230 
dnrhul/i? nnestae MATifiarn 
dnrhul !m? palliseri MfiT.ea.rn 
Unio natosini McLearn. 
Unto hamili McLearn. 
Unio cf. hamili McLearn. . ... 
TTnin dniiglasati St.fi.nt.nn 
— — 
— — 
Unio sp. 
Ynrnigr TTnin ? , , 
Campeloma? sp. 
Planorbis sp. .... . 
Ostracoda 
subtraction from 1,860. 
The lowest known fossiliferous horizon is about 230 feet above the 
base of the formation, on Lyon creek, where a bed of fossiliferous, yellow- 
weathering, conglomeratic sandstone contains Unio natosini and U. cf. 
hamili. The latter is very similar to a species in the Hillcrest Unio bed 
described below. About 520 feet above the base of the formation and 
also on Lyon creek fossils are found in two layers between two thick 
calcareous beds. The lower layer, CB.1, consists of shale and argillaceous 
limestone and contains indeterminate Corbulat, young Unio 1 !, and Planorbis. 
This is a somewhat different assemblage from that of the Unio bed at 230 
feet. The higher layer, CR2, is of dark shale and carries ostracods, inde- 
terminate young Unio ?, and Campeloma ? Also in the lower part of the 
formation is the bed of fossiliferous argillaceous limestone which outcrops 
on a hill south of Hillcrest; the exact horizon in the section is not known. 
This, like the lowest fossiliferous bed on Lyon creek carries adult Unio, 
i.e. f7. douglassi, U. hamili, and Unio sp. The highest known inverte- 
brates occur at an horizon about 310 feet below the top of the formation, 
or approximately 1,540 feet above the base, in dark shales, on Castle 
river, a little above the mouth of Link creek. Here Unio douglassi is 
found, which, as already noted, is also in the lower part of the formation, 
in the Hillcrest Unio bed. This highest known invertebrate-bearing bed 
is 230 feet below an occurrence of the upper or dicotyledonous angiosperm 
flora and 175 feet above the highest known occurrence, in this section, of 
the lower or primitive flora, with very rare dicotyledonous angiosperms. 
So the Blairmore formation contains several invertebrate faunules 
which vary considerably in composition. Are they merely phases or 
communities of one long ranging and little changing fauna or are they 
distinct faunas of unlike age. There is enough in common between the 
faunules to indicate that they are all probably of one fauna or at least of 
one little changing fauna. Thus U. douglassi is found both in the highest 
