Archaeology
Archaeology. Provisional chart showing approximate time relationship of certain archaeological sites and complexes in Plains area. Wedel, 1961.
Arcs
Arcs. Primary double mountain arc of western United States. Jacobs et al., 1959, p. 296.
Arcs
Arcs. Active primary and secondary arcs of South America. Jacobs et al., 1959, p. 301.
Arcs
Arcs. Active primary and secondary arcs and lineaments of North America. Jacobs et al., 1959, p. 305.
Arcs
Generalized section across an active single island arc. Jacobs et al., 1959, p. 298.
Arcs
Arcs. Possible active arcs of North America in Carboniferous time. Jacobs et al., 1959, p. 319.
Arctic Archipelago
Arctic Archipelago. Provisional divisions. G.S.C, Econ. Geol. 1, p. 398.
Arctic Archipelago
Arctic Archipelago. Geologic regions and subdivisions. G.S.C, Econ. Geol. 1, p. 407.
Arctic Ordivician fauna
Arctic Ordivician fauna (Nelson, 1959, pl. 2). Number: 1 Hormatoma (gastropod) 2 Winnipegoceras (cephalopod) 3 Lambeoceras (cephalopod) 4 Maclurites (gastropod)
Arctic Ordivician fauna
Arctic Ordivician fauna (Nelson, 1959, pl. 3). Number: 1 Cyrtogomphoceras (cephalopod) 2 Diestoceras (cephalopod) 3 Streptolasma trilobatum (solitary coral) 4 Lepidocyclus perlamellosus (rhynchonellia) 5. Aulacera undulata (columnar stromatoporoid)
Arctic Ordivician fauna
Arctic Ordivician fauna (Nelson, 1959, pl. 4). Number: 1 Bighornia patella (solitary coral) 2 Streptolasma angulatum (solitary coral) 3 Bighornia sp. (solitary coral) 4 Palaeofavasites (honeycomb coral) 5. Favasites (honeycomb coral) 6. Beatricia nodulosa (columnar stromatoporoid) 7. Billingsites (cephalopod) 8. Plaesiomys occidentalis (dinorthid)
Arctic Ordivician fauna
Arctic Ordivician fauna (Nelson, 1959, pl. 1). Number: 1 Recaptaculites (sponge?) 2 Grewingkia robusta (solitary coral) 3 Catenipora (chain coral) 4 Halysites (chain coral) 5 Manipora (chain coral) 6 Fusispira (gastropod)
