Elemental Composition of Crust

Element	Composition of crustal rocks
Oxygen	46.2%
Silicon	27.7%
Aluminum	8.1%
Iron	5.0%
Calcium	3.6%
Sodium	2.8%
Potassium	2.5%
Magnesium	2.1%
Other elements	1.7%
Total	100%

Flood Basalts and Stratigraphic Boundaries

Flood Basalts and Stratigraphic Boundaries The great continental flood-basalt lava flows exceeded 2000 cubic kilometres and comprise one form of large igneous province (LIP map). [image Columbia River Basalt Flows] Large igneous provinces are believed to have been caused by mantle plumes in the lithosphere, which injected magma into the lithosphere and erupted as huge basalt lava flows, probably within a million years or less. The Deccan, Newark, and Siberian flood basalts (each with lava volumes greater than 2 x 10^6 km^3 over periods of 1 million years or less) have been correlated with major extinction events. Extinctions could have been caused by environmental impacts of released gases – climatic cooling due to sulphuric acid aerosols, greenhouse warming caused by CO2 and SO2 gases, and acid rain. Mantle plume activity and flood basalts may also have been associated with other deleterious global geological factors, such as changes in sea-floor spreading rates, rifting events, increased tectonism and volcanism, or sea-level variations. The end-Cretaceous (Cretaceous/Tertiary or K/T boundary) mass extinction that wiped out the dinosaurs has been correlated with the impact of a 10-km diameter asteroid about 65 million years ago. Several other extinction events correlate with evidence of similar impacts.
Flood Basalt	Age Ma	Stratigraphic Boundary	Age Ma
Columbia River 0.25 x 10^6 km^3	16 ± 1 duration ~ 1 Myr	Early/Mid-Miocene [image]	16.4
Ethiopia ~1 x 10^6 km^3	31 ± 1 duration ~ 1 Myr	Early/Late Oligocene	30
North Atlantic >1 x 10^6 km^3	57 ± 1 duration ~ 1 Myr	Paleocene/Eocene(Thanetian/Selandian)	54.8 (57.9)
Deccan >2 x 10^6 km^3	66 ± 1 duration ~ 1 Myr	Cretaceous/Tertiary [image]	65.0 ± 0.1
Madagascar ? volume	88 ± 1 duration ~ 6? Myr	Cenomanian/Turonian(Turonian/Coniacian)	93.5 ± 0.2 (89 ± 0.5)
Rajmahal ? volume	116 ± 1 duration ~ 2 Myr	Aptian/Albian	112.2 ± 1.1
Serra Geral/Etendeka >1 x 10^6 km^3	132 ± 1 duration ~ 1 or 5 Myr	Jurassic/Cretaceous(Hauterivian/Valanginian) [image 1]	142 ± 2.6 (132 ± 1.9)
Antarctica >0.5 x 10^6 km^3	176 ± 1 or 183 ± 1 duration ~ 1? Myr	(Aalenian/Bajocian)	(176.5 ± 4)
Karoo > 2 x 10^6 km^3 td>	183 ± 1 duration ~ 0.5 -1 Myr	Early/Middle Jurassic [image 1, image 2]	180.1 ± 4
Newark >2? x 10^6 km^3	201 ± 1 duration ~ 0.6 Myr	Triassic/Jurassic [images]	205.7 ± 4
Siberian > 2 x 10^6 km^3	249 ± 1 duration ~ 1 Myr	Permian/Triassic [image, image 2]	248.2 ± 4.8

adapted from here.

Other flood basalts Paraña,

Geological Time Overview

Eon/time	Era	Period
The Precambrian extends through the Hadean, Archean, and Proterozoic Eons. The Phanerozoic commences with the Cambrian. Hadean Eon : 4.6 - 3.8Ga
Archean Eon : 3.8 - 2.5 Ga
3.8-3.6 Ga	Eoarchean
3.6-3.2 Ga	Paleoarchean
3.2-2.8 Ga	Mesoarchean
2.8-2.5 Ga	Neoarchean
Proterozoic Eon : 2.5 Ga ~ 542 Ma
2.5-1.6 Ga	Paleoproterozoic Era	Siderian 2.5-2.3
		Rhyacian 2.3-2.05
		Orosinian 2.05-1.8
		Stratherian 1.8-1.6
1.6-1.0 Ga	Mesoproterozoic Era	Calymmian 1.6-1.4
		Ectasian 1.4-1.2
		Stenian 1.2-1
1.0 Ga-542 Ma	Neoproterozoic Era	Tonian 1.0 Ga -850 Ma
		Cryogenian 850-635 Ma
		Vendian or Ediacaran, 635-542
Phanerozoic Eon : 542 Ma - present
542-251 Ma	Paleozoic Era	Cambrian 542-488.3
		Ordovician 488.3-443.7
		Silurian 443.7-416
		Devonian 416-359.2
		Carboniferous 359.2-299.0 Mississippian and Pennsylvanian
		Permian 299-251
251-65.5	Mesozoic Era	Triassic 251-199.6
		Jurassic 199.6-145.4
		Cretaceous 145.4-65.5

Eon/time	Era	Period	Epoch
65.5-present	Cenozoic Era	Paleogene 65.5-23.03	Paleocene 65.5-55.8
			Eocene 55.8-33.9 : ends with Grande Coupure extinction event
			Oligocene 33.9-23.03 : climate cooling begins by end of epoch
		Neogene 23.03-present	Miocene 23.03-5.332
			Pliocene 5.332-1.806
			Pleistocene 1.506-.005
			.005- present

Geological Time

Eon/time	Era	Period / comment	Epoch / comment
Hadean Eon : 4.6 - 3.8Ga
Archean Eon : 3.8 - 2.5 Ga
3.8-3.6 Ga	Eoarchean	Vaalbara Ur Kenorland	abiogenesis stromatolite reefs
3.6-3.2 Ga	Paleoarchean
3.2-2.8 Ga	Mesoarchean
2.8-2.5 Ga	Neoarchean
Proterozoic Eon : 2.5 Ga ~ 542 Ma
2.5-1.6 Ga	Paleoproterozoic Era	Siderian 2.5-2.3	evolution of oxygenic photosynthesis continents stabilized
		Rhyacian 2.3-2.05
		Orosinian 2.05-1.8
		Stratherian 1.8-1.6
1.6-1.0 Ga	Mesoproterozoic Era	Calymmian 1.6-1.4	Rodinia starts to assemble evolution of sexual reproduction
		Ectasian 1.4-1.2
		Stenian 1.2-1
1.0 Ga-542 Ma	Neoproterozoic Era	Tonian 1.0 Ga -850 Ma	glaciations dubbed "Snowball Earth" earliest multicelled fossils
		Cryogenian 850-635 Ma
		Vendian or Ediacaran, 635-542
Phanerozoic Eon : 542 Ma - present
542-251 Ma	Paleozoic Era	Cambrian 542-488.3	Cambrian "explosion" Gondwanaland
		Ordovician 488.3-443.7	began and ended (2nd largest) with extinction events: graptolites, first jawed fish, land plants Gondwana, Taconinc orogeny
		Silurian 443.7-416	Named for Wales. Euramerica and Caledonian orogeny graptolites, coral reefs, first bony fish, Myriapods were first terrestrial animals, first vascular plants; eurypterids; brachiopods, bryozoa, molluscs, and trilobites abundant in warm seas
		Devonian 416-359.2	"Age of Fishes", first sharks, first ammonites; land - first tetrapods, insects, spiders, and seed-bearing plants
		Carboniferous 359.2-299.0	Pangaea assembling, Hercynian and Alleghanian orogenies Mississippian and Pennsylvanian separated by an unconformity: cyclothemic coal deposits, widespread epicontinental seas and carbonate depostion. Insect and amphibian gigantism. Foraminifera prominent.
		Permian 299-251	Pangaea. Permian-Triassic extinction event (largest) with loss of 90% to 95% of marine species and 70% of all land organisms
251-65.5	Mesozoic Era	Triassic 251-199.6	starts and ends with extinction events, adaptive radiation after P-T extinction; angiosperms, pterosaurs
		Jurassic 199.6-145.4	Pangaea break-up "Age of Dinosaurs"
		Cretaceous 145.4-65.5	Named for chalk (coccolith) deposits of France and South England K-T boundary extinction event - Chicxulub impact crater
65.5-present	Cenozoic Era	Paleogene 65.5-23.03	Paleocene 65.5-55.8 (mammals)
			Eocene 55.8-33.9 : ends with Grande Coupure extinction event first modern mammals
			Oligocene 33.9-23.03 : climate cooling begins by end of epoch
		Neogene 23.03-present	Miocene 23.03-5.332 Horses, mastodons, first apes
			Pliocene 5.332-1.806 Australopithecus, Homo habilis
			Pleistocene 1.506-.005 glaciations, megafauna, anatomically modern humans
			.005- present end of recent glaciation, rise of civilization

Lagerstätten & Biota

Lagerstätten are fossil beds that contain particularly well preserved fossils.
Lagerstätte	Period	Location	Comments
Proterozoic
Doushantuo Lagerstätte	Neoproterozoic, Vendian	South China	phosphatized microbial pseudomorphs [1]: algal thalli, acritarchs, and globular microfossils interpreted as animal embryos [2] (peripatus)
Ancient Stromatolite Reefs		Northern Canada possesses some of the best preserved examples of Proterozoic reefs and other carbonates anywhere in the world. .[Precambrian pinnacle reef, NWT ; Steep Rock Stromatolites]
Ediacara Biota, Ediacara, Australia		Ediacara Hills (SA); White Sea (Russia); Mistaken Point Formation (Nfld, Canada); Charnwood Forest, UK; South America, Namibia, South China
Cambrian Lagerstätten
Sirius Passet Formation	Early Cambrian, 515-520 Ma	Greenland	oldest of major Cambrian lagerstätten (peripatus)
Chengjiang Lagerstatte, Chengjiang	Lower Cambrian, 515 to 520 Ma	Yunnan Province, China: Qiongzhusi Formation	soft-tissue fossils of algae, medusiform metazoans, chondrophorines, sponges, chancelloriids, ctenophores, cnidarians, nematomorphs, priapulid worms, hyoliths, possible ectoprocts, inarticulate brachiopods, annelid-like animals, anomalocharidids, onychophorans, arthropods, occassional trilobites, echinoderms, ‘hemichordates’ and probable early chordates
Burgess Shale	Middle Cambrian, 505 Ma	BC, Canada
Wheeler Shale	Middle Cambrian	Utah, USA: House Range	University of California, Berkeley, web page
Andrarum Limestone	Middle Cambrian	Sweden
'Orsten'	Late Cambrian	Sweden
Ordovician
Beecher’s Bed	Early Ordovician	Utica, NY state, USA
Soom Shale	Late Ordovician	Cape Province, South Africa	[1] Soom Shale, South Africa
Silurian
Much Wenlock Limestone	Early Silurian	Wales	600 species of well-preserved invertebrates: crinoids, corals, brachiopods, trilobites, algae and bryozoans
Ludford Lane Bonebed	Early Silurian	Shropshire, Welsh Borderlands	oldest known terrestrial ecosystem : vascular plants, centipedes, kampecarid myriapods, arthropleurid, trigonotarbid, arthropod fragments
Fiddler’s Green Formation	Early Silurian	NY state, USA	eurypterid beds
Waukesha [1]	Early Silurian Llandovery-Wenlock	Wisconsin, USA	arthropods and conodonts [1]
Lesmahagow	Middle Silurian	Scotland	arthropods and fish
Devonian
Rhynie Chert	Early Devonian	Scotland	hot spring deposits
Hunsrück Shale(Hunsrückschiefer)	Early Devonian (Late Pragian to Early Esmian)	Rhine and Moselle Valleys,
Gilboa	Middle Devonian	NY state, USA	spiders and pseudoscorpions
Escuminac Bay	Late Devonian (Early Frasnian)	Eastern Canada	anaspids, placoderms, and other fishes including Eusthenopteron
Canowindra	Late Devonian	NSW, Australia	fish
Cleveland Shale	Late Devonian (Fammenian), 360 Ma	Ohio, USA	vertebrate sharks
Gogo Formation	Upper Devonian (Frasnian), 350 Ma	The Kimberley, NW Australia	placoderm fish
Carboniferous
East Kirkton	Early Carboniferous	Scotland	hot spring deposits; plants; arthropods (scorpions); amphibians and reptiles
Scottish ‘Shrimp Beds’	Early Carboniferous	Scotland	crustaceans, conodont animals, tomopterid worms, fish
Loch Humphrey Burn	Early Carboniferous	Southern Scotland	terrestrial : several successive plant bearing horizons within a volcanic terrain
Mazon Creek	Late Carboniferous	Illinois, USA	deltaic and near-shore marine
Karoo	Late Carboniferous to Triassic	Southern Africa	rich mammal-like reptile fauna from the Beaufort Sandstone
Permian
Wellington Shale	Early Permian	Kansas, USA	insects
Triassic
Gres à Voltzia	Triassic	France	deltaic deposits; terrestrial plants, insects, plus aquatic crustaceans and fish
Jurassic
Posidonia Shale	Early Jurassic	Germany
Posidonienschiefer, Holzmaden	Early Jurassic	Germany	fossil reptiles - noteably ichthyosaurs, crustaceans, cephalopods
Karatau	Jurassic	South Kazakhstan	insects, spiders, crocodiles, salamander, lizard, fish, pterosaurs, plants
Christian Malford	Middle Jurassic	England	squids
Stonefield Slates	Middle Jurassic	Oxfordshire, England	small mammal jaws and teeth
La Voulte-sur-Rhône	Middle Jurassic (Lower Callovian) ~ 160 Ma	Ardèche, France	allochthonous benthic and nektobenthic, and in situ bivalve
Purbeck Beds	Late Jurassic	England	insect fauna including dragonflies, locusts, grasshoppers, butterflies, ants and aphids
Morrison Formation	Late Jurassic	Wyoming and Colorado, USA
Solnhofen Limestone	Late Jurassic(Lower Titonian)	Germany	fine-grained lagoonal sediments; most famous for the Archeopteryx and Compsognathus fossils
Cretaceous
Santana Formation	Cretaceous	Brazil	fossil fish and pterosaurs
Sierra de Montsech	Cretaceous	Spain	fossil spiders, insects, crustaceans and vertebrates
Pierre Shale	Cretaceous (Campanian)	North Dakota, USA	arthropods, vertebrates, including mosasaurs
Hajoula Limestone	Cretaceous	Lebanon	fossil arthropods and fish
Liaoning Lagerstätte, Yixian Formation	Cretaceous (Barremian?), 120-150 Ma	Liaoning Province, China: Yixian Formation	true birds, dinosaurs, ‘feathered dinosaurs’
Las Hoyas	Lower Cretaceous (Barremian), 121-127 Ma	Cuenca, Spain	rich terrestrial and freshwater assemblage of invertebrate and vertebrate trace fossils, early angiosperms, ferns, cycads, conifers, insects, birds, fish, crocodiles, a dinosaur, amphibians and lizards
Tlayúa	Early Cretaceous, 100 Ma	Mexico	coral reef : fishes, foraminifera, sponges, gorgonids, bivalves, gastropods, belemnites, ammonites, echinoderms, crinoids, annelids, arthropods, arachnid, anispoterus, turtles, pleurosaurs, sphenodonts, lizards, crocodiles and pterosaurs
Eocene
Green River Formation	Eocene	Wyoming, USA	lacustrine fossil fish and other vertebrates
Monte Bolca	Eocene, 52 Ma	Italy	tropical marine lagoon: fishes, plants, insects
Princeton Chert	Middle Eocene, 49 mya	BC, Canada	permineralised flora
Grübe Messel Shale	Eocene	Germany	lacustrine fossil plants, vertebrates and insects
Oligocene
Florissant formation	Late Oligocene - Early Eocene	Colorado, USA	trees, plants, insects
Riversleigh Fossil Sites	Late Oligocene (25ma) to Middle Miocene (10ma) to present	Queensland, Australia	mostly vertebrates, with a few snails and insects
Pliocene/ Pleistocene
Lake Turkana	Pliocene/ Pleistocene, 4-0 Ma	Lake Turkana Basin, Kenya, East Africa	Australopithecus and Kenyanthropus, and Homo

Location
Country	Lagerstätten/Biota	Period
Africa	Namibia Soom Shale Karoo System Lake Turkana, Kenya	Proterozoic (Vendian) Late Ordovician Late Carboniferous to Triassic Pliocene/ Pleistocene, 4-0 Ma
Brazil	Santana Formation	Cretaceous
Australia	Ediacara Hills Biota, Ediacara, Australia Gogo Formation Canowindra	Proterozoic (Vendian) Upper Devonian (Frasnian), 350 Ma Late Devonian
Canada	Ancient Stromatolite Reefs Mistaken Point Formation, Nfld. Burgess Shale Escuminac Bay	Proterozoic Proterozoic (Vendian) Middle Cambrian, ~505 Ma Late Devonian (Early Frasnian)
China	Doushantuo Formation Chengjiang Lagerstätte Jehol Group Yixian Formation (Liaoning)	Proterozoic (Vendian) Early Cambrian, 515-520 Ma Early Cretaceous Cretaceous (Barremian?)
England	Charnwood Forest Vendian Biota Christian Malford Stonefield Slates Purbeck Beds	Proterozoic (Vendian) Middle Jurassic Middle Jurassic Late Jurassic
France	Gres à Voltzia La Voulte-sur-Rhône	Triassic Middle Jurassic (Lower Callovian) ~ 160 Ma
Germany	Hunsrück Shale (Hunsrückschiefer) Posidonia Shale Holzmaden Solnhofen Limestone Grübe Messel Shale	Early Devonian (Late Pragian to Early Esmian) Early Jurassic Early Jurassic Late Jurassic (Lower Titonian) Eocene
Greenland	Sirius Passet Formation	Early Cambrian, 515-520 Ma
Italy	Monte Bolca (Mt. Bolca): Musei della Lessinia web page	Eocene
Kazakhstan	Karatau	Jurassic
Lebanon	Hajoula Limestone	Cretaceous
Mexico	Tlayúa	Early Cretaceous, 100 Ma
Russia	Vendian Biota, (White Sea)	Proterozoic (Vendian)
Scotland	Lesmahagow Rhynie Chert East Kirkton Scottish ‘Shrimp Beds’ Loch Humphrey Burn	Middle Silurian Early Devonian Early Carboniferous Early Carboniferous Early Carboniferous
South America	Vendian Biota	Proterozoic (Vendian)
Spain	Sierra de Montsech Las Hoyas	Cretaceous Lower Cretaceous (Barremian), 121-127 Ma
Sweden	Andrarum Limestone 'Orsten' Beds	Middle Cambrian Late Cambrian
USA	Wheeler Shale ‘Beecher’s Bed’ Fiddler’s Green Formation Waukesha Gilboa Cleveland Shale Mazon Creek Wellington Shale Morrison Formation Pierre Shale Green River Formation	Middle Cambrian Early Ordovician Early Silurian, 425 Ma Early Silurian Middle Devonian Late Devonian (Fammenian) Late Carboniferous Early Permian Late Jurassic Cretaceous (Campanian) Eocene
Wales	Much Wenlock Limestone Formation Ludford Bonebeds	Early Silurian Early Silurian

Also Dominican Amber :

Minerals & Rocks: Minerals

		magnetite
		quartz

Minerals

mineral / chemical formula	properties / significance	occurrence
magnetite (lodestone)Fe2O3	black ferrimagnetic mineral in the spinel group, converts to hematite on oxidation, produced from peridotites and dunites by serpentinization.	most igneous rocks and metamorphic rocks, many sedimentary rocks, widespread ore deposits, banded iron formations
quartz (silica) SiO2 [gallery, 2, 3]	silica tetrahedra, tectosilicate, hexagonal rhombohedral crystals in numerous varieties named for color and microstructure, numerous growth forms	commonest mineral, igneous, sedimentary, and metamorphic rocks, hydrothermal veins and pegmatites, granite, sandstone, limestone

Minerals & Rocks: Carbonates

Carbonates of iron, sodium, calcium, and calcium/magnesium:

Composition	Formula	Mineral name	Rock
iron carbonate	FeCO3	Siderite	Ironstone
sodium bicarbonate	NaHCO3	Baking soda	Nahcohlite
calcium carbonate	CaCO3	Calcite	Limestone
calcium, magnesium carbonate	(Ca, Mg)CO3	Dolomite	Dolostone

Minerals & Rocks: Evaporates, Sulphates

Evaporation of brines and salines results chemically deposited rocks, including:

Composition	Formula	Mineral	Rock
hydrated calcium sulfate	CaSO4 & 2H2O	Selenite	Gypsum
sodium chloride	NaCl	Halite	Rock salt

Minerals & Rocks: Metamorphic

Metamorphic rocks result from the subjection of a protolithic parent rock (igneous, sedimentary, or metamorphic) to heat and/or pressure and/or chemically active fluids. Metamorphic rocks are classified according to the parent rock and the degree of deformation to which the rocks have been subjected. Metamorphism occurs locally (contact) or on a large scale (regional).

Sedimentary rock	Metamorphic product (low to high grade)
Conglomerate	Meta-conglomerate, schist, gneiss
Breccia	Meta-breccia, schist, gneiss
Sandstone	Quartzite, mica schist
Shale/siltstone/claystone	Phyllite, slate, schist, gneiss, "fubarite"
Limestone/dolostone	Marble (color shows "argillaceous" or "carboniferous")
Black shale	Black slate
Peat/coal	Anthracite through graphite with or without associated natural gas, petroleum and asphalt; Mississippi-type lead and zinc deposits

Chemical metamorphic rocks:

Composition	Mineral Name	Rock Name/Ore
Au	Gold	Gold Ore
Ag	Silver	Silver Ore
Cu	Copper	Copper Ore
Pt	Platinum	Platinum Ore
S	Sulfur	Native Sulfur
CaF2	Fluorite	Fluorospar

Deposition of metals results from regional metamorphism, volcanism, hydrothermal vents, and sulphide solutions:

Composition	Mineral Name	Rock Name/Ore
PbS	Galena	Lead
ZnS	Sphalerite	Zinc
FeS2	Pyrite/Marcasite	Iron
(Cu,Fe)S2	Chalcopyrite	Copper

Solutions of hot water chemically alter carbonates and silicates:

Composition	Mineral Name	Rock Name
SiO2 transparent	...	Quartz, rock crystal
SiO2 translucent	...	Jasper, flint, chert, quartz, chalchedony, agate, silicified fossils, petrified wood
CaCO3	Calcite	Travertine marble, geodes, stalactites/stalagmites

Minerals & Rocks: Oxides

Oxides form as a result of chemical weathering (by oxygen and water) of iron and aluminum containing minerals:

Composition	Formula	Mineral name	Rock name
iron oxide	Fe2O3	Hematite	Iron ore
iron oxide	Fe3O4	Magnetite/Lodestone	Iron ore
hydrated iron oxide	2Fe2O3 & 3H2O	Limonite	Rust/iron ore
hydrated aluminum oxide	Al2O3 & 2H2O	Bauxite	Aluminum ore
aluminum oxide	Al2O3	Corundum	Ruby/sapphire

Radiometric Dating

Radiometric dating employs known rates of radioactive decay from a radioactive parent to its stable daughter element to estimate the age of a sample. Mass number is the total number of protons plus neutrons in an isotope of an element. α-decay reduces the mass number by 4, β-decay does not alter mass number (K-40 → Ar-40), γ-decay reduces mass number by 1. Elements may decay from radioactive parent to stable daughter through intermediate isotopes in a decay chain called a radioactive series. For the purposes of geological radiometric dating, ratios of radioactive-parent : stable-daughter provide sufficient information to estimate the length of elapsed time since an igneous rock containing radioactive elements cooled and solidified from magma or lava. Each radioactive isotope (atoms of the same element differing in neutron number) has its own unique half-life, which is the time required for half of the parent radioactive element to decay to a daughter product. Radioactive decay occurs at a constant exponential or geometric rate, so half of parents will decay to daughters (1:1) in one half life and one half of the remaining parents will decay in the next half life (1:3). Geologists estimate the length of time over which decay has occurred by measuring the ratio of radioactive parent element and stable daughter elements. Radioactive elements tend to become concentrated in the residual melt during the crystallization of igneous rocks, so traces of a radioactive mineral in an igneous rock will 'set the clock' at the time of cooling/solidification.
Radioactive elements and half-lives
radioactive parent	stable daughter	half-life
Sm-147	Nd-143	106 billion years
Rb-87	Sr-87	48.8 billion yrs
Re-187	Os-187	42 billion yrs
Lu-176	Hf-176	38 billion yrs
Th-232	Pb-208	14 billion years
U-238	Pb-206	4.47 billion years
K-40	Ar-40	1.26 billion yrs
U-235	Pb-207	704 million years
Be-10	B-10	1.52 million yrs
Cl-36	Ar-36	300,000 years
U-234	Th-230	248,000 years
Th-230	Ra-226	75,400 years
C-14	N-14	5715 years = useful on materials less than 70,000 years old.

Tectonic Plate Boundaries

The lithosphere is divided into tectonic plates (im) that move, albeit very slowly, in relation to each other – converging, diverging, riding over/under one another, and sliding past one another.
type of boundary	associated phenomena and structures
converging plates
arc-continent (ocean-ocean)	volcanic island arc, volcanoes, submarine trench, folding and faulting, subduction zone
ocean-continent	submarine trench, magmatic arc, folding and faulting, subduction zone
continent-continent	folding and faulting, orogeny
diverging plates
ocean-ocean	mid-ocean ridges (spreading centers, im, Iceland), volcanoes
continent-continent	rift valleys, volcanoes
subduction zones
arc-continent	volcanic island arcs, very deep earthquakes
ocean-continent	volcanic chains, very deep earthquakes
transform-boundary faults (im)
ocean-ocean	shallow earthquakes, strike-slip faults
continent-continent	shallow earthquakes, strike-slip faults

Weathering of Minerals

The mode of weathering influences the minerals that are formed from weathering of rocks.

Mineral	Physical weathering	Chemical weathering
Quartz	sand-sized particles	soluble silica
Feldspars/micas	clay-sized particles	soluble salts/soluble silica
Fe+/Mg+	black sands	soluble Fe+ and Mg+ ions

Volcanoes

Volcanoes form where heated material escapes from the Earth's crust.
Type of eruption named for	Features structure; ejection; effusion	gas/silica content of lava
Hawaiian Hawaiian island shield volcanoes	spatter cones and ramparts; very broad, flat lava cones; very weak ejection of fluid blobs, cow-dung bombs and spatter, very little ash; followed by often extensive flows of low viscosity (fluid) lava	low gas/low silica
Basaltic flood	spatter cones and ramparts; very broad, flat lava cones, lava plains; very weak ejection of fluid blebs and cow-dung bombs and spatter, very little ash; followed by voluminous, wide-spread flows	low gas/low silica
Strombolian Stromboli	cinder cones; weak to violent ejection of pasty fluid blebs, spherical to fusiform bombs; cinder; small to large amounts of glassy ash; thicker, less extensive flows of moderately fluid lava; flows may be absent	↓ increasing gas/higher silica
Vulcanian Vulcano Soufriere Hills	ash cones, block cones, block-and-ash cones; moderate to violent ejection of solid hot fragments of new lava; essential, glassy to lithic, blocks and ash, pumice; lava viscous, so flows commonly absent, thick and stubby if present, ash flows rare
Peleean Mt. Pelee	ash and pumice cones; domes; explosive activity like Vulcanian, commonly with glowing avalanches; domes and/or short, very thick flows of viscous lava; flows may be absent
Plinian Pliny the Elder, who died during the eruption of Vesuvius	widespread pumice lapilli and ash beds; generally no cone-building; ejection of large volumes of ash, with accompanying caldera collapse, ejecta are glassy ash and pumice; magma very viscous, so ash flows, small to very luminous, or effusive activity may be absent
Rhyolitic flood	flat plain, or broad, flat shield, often with caldera; relatively small amounts of ash projected upward into the atmosphere; ejecta are glassy ash and pumice; viscous magma, so effusive activity confined to relatively small amounts of ash projected upward into the atmosphere	Rhyolite
Ultravulcanian	block cones; block-and-ash cones; weak to violent ejection of solid fragments of old rock; ejecta are accessory and accidental block and ash; no magma and no lava effusion
gas eruptions	continuous or rhythmic gas release at vent; no ejecta or very minor amounts of ash, no magma
fumarolic	generally no structure, rarely very small ash cones; no ejecta or rarely very minor amounts of ash; no magma, nonexplosive weak to moderately strong long-continued gas discharge