FOSSILS IN THE GASTINEAU CHANNEL FORMATION
Southeast Alaska

 

Marine Fossils of the Gastineau Channel Formation

BIVALVIA
   Astarte alaskensis Dall
   Astarte montagul (Dillwyn)
   Chlamys rubida (Hinds)
   Clinocardium ciliata (Fabricius)
   Cyclocardita ventricosa (Gould)
   Hiatella arctica (Linnaeus)
   Macoma brota Dall
   Macoma calcarea(Gmelin)
   Macoma obliqua (Sowerby)
   Mya truncata Linnaeus
   Mytilus edulis

Nucula tenuis (Montagu)
   Nuculana fossa (Baird)
   Nuculana minuta (Fabricius)
   Nuculana pernula (Muller)
   Parvamussium alaskensis (Dall)
   Protothaca staminea (Conrad)
   Saxidomus gigantea (Deshayes)
   Serripes groenlandicus (Bruguiere)
   Tresus capax (Gould)

GASTROPODA
   Acmaea mitra Rathke
   Admete couthouyi (Jay)
   Boreotrophon beringi (Dall)
   Buccinum kadiakense Dall
   Colus halli Dall
   Cryptobranchia concentrica(Middendorff)
   Cylichna alba (Carpenter)
   Fusitriton oregonense (Redfield)
   Natica clausa Broderip & Sowerby
   Neptunea lyrata Gmelin
       Nucella canaliculata (Duclos)
   Nucella lamellosa (Gmelin)
   Ocenebra lurida (Mlddendorff)
   Oenopta harpularia (Couthouy)
   Puncturella galeata (Gould)
   Tectura persona (Rathke)
   Trichotropis borealis Broderip & Sowerby
   Trichotropis cancellata Hinds
CRUSTACEA
   Balanus nubilis Darwin
   Balanus spp.
   Ostracoda
BRACHIOPODA
   Laqueus californianus (Koch)
POLYCHAETA
   Serpula vermicularis Linnaeus
   Sinistrella sp.
   Spirorbissp.
BRYOZOA
   Heteropora alaskensis (Borg
   Bryozoa spp
ECHINODERMATA.
   Urchin fragments
PORIFERA
   Spicules
   Spicula matrix

Station Location/
Sites

Caral at work in the field

The fossils in the Gastineau Channel Formation were deposited in water that was shallow (less than 150 feet), saline to brackish (35 to 27 %) and cold (0° C to 10° C). Miller (1973), Smith (1961) and Todd & Low (1967) came to this conclusion based on the tolerances of the species commonly present. Elphidium clavatum was the most abundant and wide spread foraminiferan. It tolerates variations in temperature and salinity but not greater depth. Other commonly occurring forams, while tolerant of greater depth, were less tolerant of greater temperature and salinity variations.
   Isostatic rebound has lifted Gastineau Channel Formation deposits above sea level, in some places as much as 750 feet. The highest sample taken in this study was at 300 feet above current sea level. The radiocarbon age of shell material reported by Miller (1975) was 9,500 yr BP to 12,000 yr BP.
    Sampling this formation was of necessity opportunistic. The material ranged from muddy gravel to muddy sand to sandy clay. Much of it was readily eroded. Banks exposed by road construction were later stabilized by rocks and vegetation. Material dug up to set power poles was often rich in fossils but soon vegetated. Some very solid clay samples were in streams and only available at low water. Ditch cleaning by the road department exposed some sites that would have been missed otherwise.
    Macro fossils were picked from the surface when exposed and from the screens used to process the foraminifera samples. Approximately a cup (200— 300 g. dry weight) of blue—gray sandy mud was dried then rewetted to soften the clods. The material was washed through four screens with sizes and mesh openings of #18 (1.0 mm), #35 (0.5 mm), #70 (0.212. mm) and #140 (0.106 mm).
    The material from each screen was examined under a dissecting microscope. Forams and other micro— fossils were picked and identified. A sample size of over 200 forams was considered adequate to characterize the site. Some samples had fewer than 200 and many had more.
    The sample sites in this study showed a range of habitats from a high energy site with strong currents to moderate energy sites and low energy sites with deposition instill water. Diversity was greatest in the low energy sites and moderate to low in the moderate energy sites. The single high energy site had species adapted to live in stronger currents.
    Following are sections on the macrofossils, foraminifera and descriptions of the sample sites. The bibliography includes references on the Gastineau Channel Formation and keys used to identify the fossils.

Station Location/
Sites

Foraminifera

FAMILY
Saccamminidae
Saccamina difflugiformis (Brady)
Reophacidae
Reopax insectus (Goes)

Lituolidae
Recurvoides turbinatus (Brady)
Valvulinidae
Eggerella advena (Cushman)
Miliolidae
Quinqueloculina agglutina Cushman
Quinqueloculina akneriana d’Orbigny
Quinqueloculina arctica Cushman
Quinqueloculina stalkerl Loebflch & Tappan
triloculina trihedra Loeblich & Tappan
Pyrgo lucernula (Schwager)
Opthalmidiidae
Cornuspira involvens (Reuss)
Lagenidae
Dentaliria baggi Galloway & Wissler
Laevidentalina californica (Cushman & Gray)
Lagena distoma Parker & Jones
Lagena gracillima (Seguenza)
Lagena laevis (Montagu)
Lagena meridionalis Wiesner
Lagena mollis (Cushman)
Lageria parri Loeblich & Tappan
Lagena semilineata Wright
Lagena setigera Wright
Lagena striata (d’Orbigny)
Lagena tenuis (Bornemann) var. Ornata Reuss
Procerolagena complurecosta (Patterson)
Pollymorphinidea
Laryngosigma hyalascida Loeblich & TappanBuliminidae
Buliminella subfusiformis Cushman
Globobulimina aurculata ssp arctica (Bailey)
Virgulina fusiformis (Williamson)
Bolivina decussata Brady
Bolivina pacifica Cushman & McCulloch
Fissurina cucurbitasema Loeblich & Tappan
Fissurina lucida (Williamson)
Fissurina marginata (Montagu)
Oolina apiopleura (Loeblich & Tappan)
Oolmna laevigata d’Orbigny
Oolina melo d’Orbigny
Oolina striatopunctata (Parker & Johnson)
Angulogerina fluens Todd
Spirillinidae
Patellina corrugata Williamson
Rotalidae
Buccella frigida (Cushman)
Buccella tenerrima (Brady)
Epistominella pacifica (Cushman)
Epistominella vitrea Parker
Elphidiidae
Elphidiella nitida Gushman
Elphidium clavatum Cushman
Elphidium frigidum
Cushman
Elphidium oregonense
Cushman&Grant Anomalinidae
Cibicides lobatulus (Walker&Jacob)
Nonionidae
Nonion labradoricum (Dawson)