Pika Formation, Middle Cambrian, (lower Marjuman), Alberta and B. C., southern Rocky Mountains, Canada
Trilobites:
Olenoides cf. O. pugio Fauna:
Glyphaspis sp. 1 (see Melzak and Westrop, 1994)
Marjumia sp. (see Melzak and Westrop, 1994)
Olenoides cf. O. pugio (Walcott, 1908)
Glyphaspis tetonensis Fauna:
Glyphaspis
tetonensis (Resser, 1937)
Knechtelia festiva (Lochman and Hu, 1960)
Bolaspidella resseri Zone:
Bolaspidella
resseri (Miller, 1936)
Glyphaspis sp. 2 (see Melzak and Westrop, 1994)
Glyphaspis? cf. G.? curticei (Resser, 1938)
Gen. and sp. indet. 2 (see Melzak and Westrop, 1994)
Plagiura? cf. P. retracta Zone:
Marjumia
bagginsi (Melzak and Westrop, 1994
Marjumia cf. M. transversa (Palmer, 1968)
Plagiura? cf. P. retracta (Palmer and Halley, 1979)
Spencella cf. S. montanensis (Rasetti, 1963)
Gen. and sp. indet. 1 (see Melzak and Westrop, 1994)
Comments:
The Pika Formation outcrops in the Rocky Mountains in Banff and Jasper National Park in the Alberta-British Columbia border area. Almost all known outcrops are in Canada's Rocky Mountain Parks, so collecting is forbidden. This Formation is bounded below by the Eldon Formation, and above by the Arctomys Formation. It is interpreted as an inner shelf setting and has a low diversity trilobite fauna (8 gen., 13 spp.). It has been divided into 2 Zones and 2 informal faunas which are Marjuman in age.
The Pika is correlated with the Park Shale and adjacent units in the Wind River Mountains of Wyoming (Lochman and Hu, 1960 among others). These Wyoming units have species in common. It also correlates (less directly) with the deeper water Marjum Formation (House Range, Utah).
"The Chaba River section of the Pika Formation (collected by Fritz and Aitken of the GSC) includes localized high-quality silicified trilobite remains. Extracted by HCl etching, the fauna yielded a complete ontogenetic series (protaspides - holaspides) for Glyphaspis tetonensis and an apparently complete series for Knechtelia festiva (protaspides indistinguishable). The collections also included ventral elements. A nonsilicified fauna from Windy Point (Fritz and Aitken coll.) also included protaspides of G. tetonensis." (Melzak, pers. comm.)
Trivia: The species Marjumia bagginsi was named after the hobbit Bilbo Baggins.
References:
Melzak,
A. and Westrop, S. R. (1994) Mid.-Cambrian (Marjuman) trilobites from the
Pika Formation, southern Canadian Rocky Mountains, Alberta. Canadian Journal of
Earth Sciences, Vol. 31, pp. 969-985.
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