RESEARCH· ·1970·

B122
PALEONTOLOGY
Tetrataxis sp.
Tetrataxis of the group T. eominima Rauzer-Chernoussova
Tuberitina sp.
The appearance of abundant Asteroarohaedisous
mixed with Neoarohaedismts and Planospirodisous indicates
an early Namurian age (Chester, Zone 17) for
the assemblage. The interval is about the same age as
that of the basal part of the Surrett Canyon Formation
in the Lemhi (Huh, 1967, 1968) and Lost River
Ranges, and the middle part of the Etherington Formation
of southwestern Alberta C~1amet, 1968). It is
also the time-stratigraphic equivalent of some of the
upper part of the ~1onroe Canyon Limestone of southeastern
Idaho and member F of the Diamond Peak
Formation of east-central Nevada. The mode of origin
of the interbedded quartzose chistic rocks and the
bioclastic limestone is the same as that described for
the underlying beds of Zone 16s.
The uppermost 300 feet of limestone, unit a (part),
exposed in the Cabin Creek section is rich in microfauna.
The microfauna consists of the following genera
and species:
Asteroarohaedisous sp.
Asteroarohaedisous of the group A. basohkirious
( J(restovnikov and Teodorovich)
Oaloisphaera sp.
Oaloisplwe1·a laevis 'Villiamson
Olimaoammina sp.
E arlandia sp.
Endothyra sp.
Endothy1·a of the group E. bowmani Phillips in
Brown emend Brady
Endothyra exoellens (Zeller)
Endothyranopsis sphamioa (Rauzer-Chernoussova
and Reitlinger)
E ostaffella sp.
Globivalv~tlina ~ sp.
Globivalv~tlina ~ ]Jarva Chernysheva
K oskinobigenmina sp.
N eoarchaedisous sp.
N eoarohaediso~t8 inoertus ( Grozdilova and Lebedeva)
cf. 11/ illerella ~ sp.
Palaeotextttlaria sp.
Planospirodismts sp.
Psettdoendothyra sp.
Psettdoendothyra of the group P. oirmtli (Thompson)
Pse~tdoendothyra
Rozovskaia
Tttberitina sp.
of the group P. krenwnskensis
The first appearance of abundant Globivalvulina ~
parva mixed with Aste1~oa1·ohaedismts indicates a late
early Namurian age (Chester, Zone 18). The succession
is the time-stratigraphic equivalent of part of the Surrett
Canyon Formation in the Lemhi and Lost River
Ranges, south-central Idaho (fig. 2), and the uppermost
part of the 1\1onroe Canyon Limestone in the
Chesterfield Range, Idaho. It is also equivalent to the
upper part of the Etherington Fonnation of Alberta
( ~1amet, 1968) .
The top of the 'Vhite J(nob succession at the type
locality is eroded, and no equivalent of the E osigmoilina
~ Zone 19 fauna, which is present at the top of the
Surrett Canyon Formation in the Lost River Range,
has been found. Tertiary Challis Volcanics lie with
angular unconformity on the eroded carbonate
sequence.
CONCLUSJONS
Reexamination in the field and reevaluation of the
microfauna of the Cabin Creek section, the type locality
of the 'Vhite J(nob Lin1estone designated by Ross
(1962) in south-central Idaho, have shown that a minimum
of 5,500 feet of interbedded limestone, sandstone,
and conglomerate is present above the ~1illigen Formation
and that the age range of the succession is Visean
and early Namurian (Late ~1i~sissippian). Foraminiferal
Zones 16t through 18 (Chester), as used by ~1amet
( 1968) in the Canadian Cordillera, are present and
well developed. Strata in the vVhite Knob below Zone
16 1 are known to be Zone 13 ( 1niddle ~1era1nec) or a
younger· zone. Chert- and quartzite-pebble conglomerates
in the section, which firf:?t appear in Zone 16s
(Chester, latest Visean) , extend through Zone 17
(Chester, early Namurian) and are the tiine-stratigraphic
equivalents of a part of the Diamond Peak
Formation in east-central Nevada (Brew, 1970).
Lithologies of the lower part of the type White
Knoh· Limestone above the argillites .o,f the Milligen
Formation are very similar to those of the ~1iddle Canyon
Formation and the lower part of the Scott Peak
Formation iri the Len1hi and Lost River Ranges of
Idaho. The overlying beds are lithologically dissimilar
to the formations of Huh, in that they contain interbedded
conglomerate and sandstone; but they are the
temporal equivalents of the upper strata of the Scott
Peak :Formation, the entire South Creek Formation,
and 1nost of the Surrett Canyon Forn1ation of Huh as
exposed in the Lost River and Lemhi Ranges, Idaho
(Huh, 1967, 1968). The 'Vhite J(nob beds above the
fault zone in the type locality are also probably equivalent··
to the entire 1\1onroe Canyon Limestone of the
Chesterfield Range Group in southeastern Idaho
(Sando and others, 1969).