INDEX 599 Archaeocidaris 2:355 archaeocyathans 4:565 Archaeoellipsoides 4:368 Archaeolithophyllum 2:434, 2:435f archaeological geology See geoarchaeology Archaeopteris 4:195 Archaeopteris bibernica 2:445, 2:445f Archaeopteryx 2:497, 3:358-359 Archaeopteryx lithographica 2:172 Archaeoscillatoriopsis disciformis 4:3 69f Archaeothyris 2:487 Archeria crassidisca 2:476-477 arches 4:579f archosauromorphs 2:484 arc magmatism Andes Mountains 1:118-131 granitic rocks 3:237* Grenville orogeny 3:155-156, 3:157 Northern Appalachians Notre Dame arc 4:85, 4:87f Popelogan-Victoria arc 4:#2/", 4:57/1, 4:89 Victoria arc 4:82f northern Cordillera 4:44 ocean trenches 5:431 Arctic Caledonides 2:71f, 2:72f Arctic Sea 2:108 Arctic Shelf 4:464, 4:464f Ardennes 2:75, 2:81f, 2:83-84 Ardipithecus 2:541 Ardipithecus ramidus 5:49It Ardmore Basin 4:32/", 4:66f Arduino, Giovanni 3:170 Arecibo Observatory, Puerto Rico 5:244-245 Arenicolites 4:224 Arenigian subdivision 4:84f, 4:87f, 4:175-176, 4:177, 4:177f, 4:178-179 aretes 4:670, 4:672^ Areyongia 2:462 arfvedsonite 3:505-506 Argand, Emile 2:240, 2:252, 3:193 Argentina 1:153-163 Andes Mountains fold-and-thrust belts Cordillera Principal belt 1:158 Fueguian fold-and-thrust belt 1:159 general discussion 1:158 Patagonia fold-and-thrust belt l:125f, 1:128, 1:158 Santa Barbara fold-and-thrust belt 1:127,1:158 Sierra Pampeanas belt 1:130, 1:158 sub-Andean fold-and-thrust belt 1:127, 1:158 geochemical analysis 1:157f volcanism 1:157 background information 1:153 borate deposits 3:513t Cambrian l:156f Carboniferous glaciation 4:208f Cenozoic l:156f flying reptiles 2:514 geological settings Aconcagua 1:153, l:155f Andes Mountains 1:153 central segment 1:153 digital elevation map 1:154f fold-and-thrust belts 1:156 foreland basins 1:153-156 morphology 1:155f Nazca Plate 1:155f northern segment 1:153 orogenic belts 1:156f southernmost segment 1:157 southern segment 1:156 volcanism 1:153, 1:156 Gondwana 3:128 Grenville orogeny l:156f, 1:161-163 Mesozoic Choiyoi Province 1:161 Chon Aike Province 1:161 general discussion 1:161 orogenic belts 1:156f rift systems 1:162f Palaeozoic Chilenial:160/", 1:163 Cuyanial:160/", 1:161 orogenic belts l:156f Pampial:160/, 1:163 Patagonia l:160f, 1:163 terranes 1:161 Proterozoic l:156f Silurian 3:136f stable platform cratons 1:160 f general discussion 1:159 sedimentary basins Chaco-Parana basin 1:159 Colorado basin 1:159 Salado basin 1:159 San Jorge basin 1:161 terranes 1:160 f uplift areas 1:159 Triassic 3:345-346 wine geology 2:87f argentite (Ag2S) 3:575*, 3:582f, 3:630t argentopyrite 3:575* argillaceous sediments See clays Argo Basin 3:316t Argo Land 3:147 argon (Ar) atmospheric concentrations 1:1971, 1:198, 1.-199/", 3:553 mantle sources 3:228 natural occurrences 3:553* radiometric dating absolute dating techniques 1:88t Carboniferous stratigraphy 4:202f geoarchaeology 3:20 geological time-scale 5:518 glauconite 3:547 sedimentary rocks 5:146, 5:147/, 5:69 Venus 5:246* Arias intensity 1:505, 1:505f aridisols 5:196*, 5:200 arid regions See deserts Ariel 5:290-291, 5:291* Arikareean stage 5:473/", 5:478, 5:479f aristarainite (Na2MgB12O2o- 8H2O) 3:513* Aristarchus (lunar crater) 5:271 Aristotle 3:168 Arizona, United States 4:48-50, 4:55-56, 5:207f, 5:476-477 Arkansas, United States 4:61-71 Arkoma Basin 4:64f, 4:66f, 4:67, 4:68f Arkona Basin 2:156f arkoses 5:27*, 5:29f Armenia 4:215-216 Armorica Armorican Massif Anisian-Ladnian/Muschelkalk palaeogeography 2:110f Aptian-Albian palaeogeography 2:116f Baj ocian-Bathonian palaeogeography 2:112f Berriasian-Valanginian palaeogeography 2:115f Kimmeridgian-Tithonian palaeogeography 2:114f Oligocene2:121/" Palaeocene2:119/" Rhaetian-Hettangian palaeogeography 2:111 f Scythian-Bundsandstein palaeogeography 2:109f Senonian-Danian palaeogeography 2:118f Variscides Orogeny 2:75 Armorican Terrane Assemblage 2:75-85, 5:455 Caledonian Orogeny 2:59 Central Armorican Basin 2:96 Devonian 2:78, 2:79 Ordovician 2:78 palaeogeographic reconstruction 2:77f, 4:155f, 4:155-156, 4:353f Silurian 2:78 tectonic processes 2:79, 2:80f, 2:81f, 2:82f, 2:83f terranes 2:75-85, 5:455, 5:457f, 5:458f Armstrong, N 5:266* arrojadite 5:125-126 arsenic (As) arsenates 3:506-510 alteration 3:508 crystal structure 3:506 nomenclature 3:506 occurrence 3:509 physical properties 3:506, 3:508f solubility 3:508 stability 3:506 hydrothermal ore deposits 5:394* mineral classification systems 3:501*, 3:502* natural occurrences 3:553*, 3:554 soil concentrations 2:22* toxicity 2:22* arsenoclasite 3:508f arsenocrandallite 3:508f