2 
HISTORY OF NOMENCLATURE 
In 1886 McConnell 1 used the term “Halysites beds” to designate 
the dolomites and quartzites above the “Graptolite beds” and assigned 
them to the Silurian. Burling 2 introduced the term “Beaverfoot” to 
apply to that part of the beds which bears a Richmond fauna. Walcott 3 
applied the name “Beaverfoot” to the “coral beds” and referred them 
to the “Silurian?”. Later, Walcott 4 used “Brisco” for the strictly 
Silurian beds and adopted Burling’s interpretation of the Richmond beds, 
comparing the fauna with that of Stony Mountain of Manitoba and the 
Bighorn of Wyoming. 
UPPER LIMITS OF THE BEAVERFOOT 
In this paper those beds are considered as Beaverfoot in which the 
Richmond fauna predominates, although it is evidently necessary to extend 
downward the limits of the range of some forms heretofore considered 
Silurian. Such forms as Streptelasma , Dinorthis, Columnaria, Halysites 
without the tubuli, and the forms of Rhynchotrema present, point definitely 
to an Ordovician age. In several localities, however, Syringopora, a 
Favosites generally regarded as Silurian, and a doubtful form of 
DiphyphyUum appear. It is clear that beds with an assemblage of char- 
acteristic Richmond genera are followed by transitional beds in which 
the Richmond fauna predominates, but is associated with later forms. 
In other words, in the Richmond seas later forms have appeared and 
continued side by side with the typical Ordovician fauna. In time, the 
forms characteristically Richmond have failed to adapt themselves to 
some change, have gradually died out, and the strictly Silurian forms have 
survived. The transition from the Richmond to the Silurian thus appears 
to have been gradual, indicating that deposition has been continuous and 
undisturbed in the areas under consideration. Besides the Syringopora , 
Favosites, and the doubtful DiphyphyUum mentioned above, there is the 
form Halysites delicatulus which first appears in the Beaverfoot beds and 
continues upward. Its presence at Canal Flats, without other associated 
fossils, does not signify anything stratigraphically. On the other hand, 
the assemblage of fossils in Harrogate area, which includes another 
form of Halysites , does arouse doubt as to the position of the horizon 
holding them, but the fauna is here treated as being Richmond, because 
though it contains more fossils of Silurian aspect than any other Richmond 
horizon, there are present some of those fossils which are more abundant 
in definitely Beaverfoot beds. 
In most of the localities it has not been possible to procure a complete 
section of the Beaverfoot, but one continuous section was measured, 6 
locality 7 on the index map (Figure 1). In this section at 268 feet above 
the base of the Beaverfoot the younger forms are first associated with 
typical Richmond forms. It is hoped that later investigations may 
produce sections elsewhere in which this line can be more definitely placed. 
1 Geol. Surv., Canada, Ann. Kept., vol. II, pt. D, pp. 15-21 (1887). 
* Geol. Mag., vol. 59, No. 700, p. 453 (1922). 
* Misc. Coll. Smith. Inst., vol. 67, No. 8, p. 463 (1923). 
* Misc. Coll. Smith. Inst., vol. 75, No. 1, p. 13 (1924). 
* For further details of this section, see Memoir 148. 
