Arcs. Active primary and secondary arcs of South America. Jacobs et al., 1959, p. 301.

Arcs. Active primary and secondary arcs and lineaments of North America. Jacobs et al., 1959, p. 305.

Generalized section across an active single island arc. Jacobs et al., 1959, p. 298.

Arcs. Possible active arcs of North America in Carboniferous time. Jacobs et al., 1959, p. 319.

Arctic Archipelago. Provisional divisions. G.S.C, Econ. Geol. 1, p. 398.

Arctic Archipelago. Geologic regions and subdivisions. G.S.C, Econ. Geol. 1, p. 407.

Arctic Ordivician fauna (Nelson, 1959, pl. 2). Number: 1 Hormatoma (gastropod) 2 Winnipegoceras (cephalopod) 3 Lambeoceras (cephalopod) 4 Maclurites (gastropod)

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 (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 (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)

Arctica ovata from the Bearpaw formation, south of Walsh, Alberta.

Map of the Netherlands showing the principle areas affected by the flood disaster of the 31 January, 1953.

Area of thin glacial cover of erratics only. Looking north towards Rock Glen, which can be seen in the valley. Highway 2, south of Rock Glen. Sunday, October 2, 1960.

"Armour lava" consisting of big, low vaults broken up mainly along radial fissures. This is common in Icelandic pahoehoe flows. Near the river Huerfisfljot. August 10, 1960.

Ashlayers (rhyolitic, white, and basic, black) exposed in pit. From bottom to top. Hekla 4 (4000 years ago, white with black), Hekla 3 (about 2700 years B.P., white), Hverfjall (about 2500 B.P., basic volcanic ash), laxa (about 2000 B.P., basic). Near Ludent crater. August 4, 1960.