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Geology Terms and _The_Book_ !

'Assembling California' was a wonderful read but contained a lot of new vocabulary for this reader. VERY interesting material. Just the chapter on the California Gold Rush was worth the price of the book.

In one of the later chapters, the geologist is describing, in text obviously, how the various pieces of today's earth all bound to each other. It was hard to visualize all the movements described. I looked for, and found, a video which models all those plate movements: Click_here (and/or save the address: https://www.youtube.com/watch?v=Cm5giPd5Uro)

There are many time period names cited in the following, so many that I added an abbreviated wikipedia table at the end. Please see geoPeriods table

I don't know if I'll ever finish defining all the terms below. I wrote each down, thinking I should follow up on definitions, connections. Maybe. Later? I've borrowed a book, "Field Geology Illustrated" to help out; it too is good but suffers from long stretches of "word salad" - meaning it's another book not written for the newbie.

accretionary wedges
forms from sediments accreted onto the non-subducting tectonic plate at a convergent plate boundary. Most of the material in the accretionary wedge consists of marine sediments scraped off from the downgoing slab of oceanic crust, but in some cases the wedge includes the erosional products of volcanic island arcs formed on the overriding plate.
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andesite
an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and rhyolite, and ranges from 57 to 63% silicon dioxide (SiO2) wikip
andesite flow
ash
asthenosphere
the highly viscous, mechanically weak and ductilely deforming region of the upper mantle of the Earth. It lies below the lithosphere, at depths between approximately 80 and 200 km (50 and 120 miles) below the surface.
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auriferous gravel
gold
basalt
The most common volcanic rock type on Earth, with an average density 3g/cm^3. More than 90% of all volcanic rock on Earth is basalt. A mafic extrusive igneous rock formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. Basalt lava has a low viscosity, due to its low silica content, resulting in rapid lava flows that can spread over great areas before cooling and solidification. The basaltic lava initially accumulated in topographic low spots such as creeks, rivers and lakes until they were buried in lava.

Gabbro and Basalt are chemically the same rock type. Gabbro is coarse grained because it cooled slowly at depth while Basalt cooled rapidly because it cooled at the Earth's surface.

'Flood basalt' describes the formation in a series of lava basalt flows. Flood Basalts are so named because of their immense volume of lava erupted on to the Earth's surface in one eruptive event. It is thought that individual events endured for months at a time.

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Basin and Range
?area near Salt Lake?
batholith
surface of at least 40 sq miles, no bottom
breccia
rock of broken minerals or rock cemented in fine grain mixture
Cambrian Period
541-485 mya. The Cambrian is unique in its unusually high proportion of lagerstätte sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian biology surpasses that of some later periods.
See geoPeriods table
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Carson Range
east of the Sierras
Cenozoic
66 mya (= million years ago).
See geoPeriods table
chalk
from clean lime ooze. Kindle_45% A soft, white, porous, sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Calcite is an ionic salt called calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores.
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chert (hard, sedimentary rock, fine grained quartz)
red? hard, sedimentary rock, fine grained quartz crystals. A hard, fine-grained sedimentary rock composed of crystals of quartz (silica) that are very small (microcrystalline or cryptocrystalline). Quartz (silica) is the mineral form of silicon dioxide (SiO2). Chert is often of biological origin (organic) but may also occur inorganically as a chemical precipitate or a diagenetic replacement (e.g., petrified wood). Geologists use chert as a generic name for any type of microcrystalline or cryptocrystalline quartz. See "siliceous ooze" below.
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clastic rock
composed of fragments, or clasts, of pre-existing minerals and rock. A clast is a fragment of geological detritus, chunks and smaller grains of rock broken off other rocks by physical weathering. Geologists use the term clastic with reference to sedimentary rocks as well as to particles in sediment transport.
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complex
copper
first smelted in China
a note in chemistry.html
Cretaceous
145 to 65 mya. see Mesozoic period
See geoPeriods table
crustal rock
forms continents. less dense than mantle rocks.
diabase
intrusive mafic rock forms dykes or sills
dike
or 'dyke'. a sheet of rock that is formed in a fracture in a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing crack. (The book's term "sheeted dikes" wasnt in Wikip; perhaps 'sedimentary'?)
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diorite
an intrusive igneous rock composed principally of the silicate minerals plagioclase feldspar (typically andesine), biotite, hornblende, and/or pyroxene. The chemical composition of diorite is intermediate, between that of mafic gabbro and felsic granite. Diorite is usually grey to dark-grey in colour, but it can also be black or bluish-grey, and frequently has a greenish cast. It is distinguished from gabbro on the basis of the composition of the plagioclase species; the plagioclase in diorite is richer in sodium and poorer in calcium. Diorite may contain small amounts of quartz, microcline, and olivine. Zircon, apatite, titanite, magnetite, ilmenite, and sulfides occur as accessory minerals. blue diorite, like slate. See photos in wiki article.
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docked
Donner Summit
Eldridge Moores
THE famous geologist who contributed the core science to the book "Assembling California" (John McPhee was the science writer). Sadly, he died in 2018. He worked for UC Davis.
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Eocene
2nd part of paleogene. 56-33 m.y. ago. part of cenozoic era.
See geoPeriods table
Eurasian plate
Farallon Plate
the eastbound plate which made Western California
Farallon Trench
fault
feldspar
silicates make up more than 40% of earth's crustal volume. lighter than mantle material
Francis Drake
Celebrated English pirate, Kindle_78%
Franciscan sediments
Kindle_60%
gabbro
cooled magma, lacks quartz.
geosyncline
a fold in the rocks where the oldest stuff ends up on top
Golconda Thrust
a major oceanic terrane that was thrust over central and northern Nevada, North America, in possibly sometime between the Late Permian and the late Jurassic. gold quartz deposits with serpentines
Golden gate bridge structure
Kindle_76% has a discussion about its quake resistant strength.
Gondwana
See bottom part of image in Tethys entry
granite
intrusive, felsic, igneous rock. fine grained structure.
granitic
granite-like rocks
ground-sluicing
Hangtown
Placerville
hardpan
hard layer of soil, usually a little below the surface. usually impervious to water.
hydraulic mining
high pressure huge volume water cannons used to move giant amounts of soil into gold rush filters.
Iapetus Ocean
Kindle_67% an ocean on the very early earth, 600 to 400 m.y. ago.
Jurassic
see Mesozoic
K-T boundary

Alvarez, irridium, dinosaurs.

See geoPeriods table

lifted mountains.
limestone
carbonate sedimentary rocks. often contain sea fossils.
lithosphere plates
lithosphere (crust + upper most solid mantle)
Loess
a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of the Earth's land area is covered by loess or similar deposits.

Loess is an aeolian (wind-related) sediment formed by the accumulation of wind-blown silt, typically in the 20–50 micrometer size range, twenty percent or less clay and the balance equal parts sand and silt[4] that are loosely cemented by calcium carbonate. It is usually homogeneous and highly porous and is traversed by vertical capillaries that permit the sediment to fracture and form vertical bluffs.
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Maastrichtian
mafic
Iron rich. Silicate mineral or igneous rock rich in magnesium and iron
magma
melt bottom of crust. eg subduction
mantle
Marin Headlands terrane
Kindle_75%
melange
SF melange mentioned Kindle_61%
Mesozoic
contained, in order, Triassic, Jurassic, and Cretacious
See geoPeriods table
metasediments
millipartite structure
mineral
broadly speaking, a solid chemical compound that occurs naturally in pure form. Minerals are most commonly associated with rocks due to the presence of minerals within rocks. These rocks may consist of one type of mineral, or may be an aggregate of two or more different types of minerals, spacially segregated into distinct phases.
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Miocene
up to 5.3 mya, between Pliocene and Ogliocene.
See geoPeriods table
Mississippian period
The Mississippian (also known as Lower Carboniferous or Early Carboniferous) is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earliest/lowermost of two subperiods of the Carboniferous period lasting from roughly 358.9 to 323.2 million years ago. As with most other geochronologic units, the rock beds that define the Mississippian are well identified, but the exact start and end dates are uncertain by a few million years. The Mississippian is so named because rocks with this age are exposed in the Mississippi River valley.
See geoPeriods table
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Moho
Kindle_39% The Mohorovicic discontinuity,usually referred to as 'the Moho', is the boundary between the Earth's crust and the mantle. Moho, petrologic Moho
"Assembling California" makes reference to 2 Moho's b/c the seismic waves seem to encounter 2 different density layers. About 39% of the way thru the kindle version.
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Monadnock
Originally a Native American term meaning an isolated rock hill, knob, ridge, or small mountain that rises abruptly from a gently sloping or virtually level surrounding plain. The German word Inselberg "island mountain"
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Mount Diablo
Jurassic rocks, upthrust fault raises mountain a few mm each year.
"complete sequence" east side Kindle_62%.
Called a "piercement structure" Kindle_73%
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Mount Everest
The very top is marine limestone! Kindle_70%
mudflow
olivine
mg fe silicate.

Wikip's photo of olivine.

This is one of the materials in the mantle.

ophiolite
column of ocean floor rock (denser than crustal rock). Kindle_42%.
orogeny
wrinkling process, eg Sonoma Orogeny. An orogeny is an event that leads to both structural deformation and compositional differentiation of the Earth's lithosphere (crust and uppermost mantle) at convergent plate margins. An orogen or orogenic belt develops when a continental plate crumples and is pushed upwards to form one or more mountain ranges; this involves a series of geological processes collectively called orogenesis. Orogeny is the primary mechanism by which mountains are built on continents. wikip
Owens valley
Pacific Plate
Pangea
formed 250 mya. Kindle_65% A supercontinent that existed during the late Paleozoic and early Mesozoic eras. It assembled from earlier continental units approximately 335 million years ago, and it began to break apart about 175 mya. In contrast to the present Earth and its distribution of continental mass, much of Pangaea was in the southern hemisphere and surrounded by a superocean, Panthalassa. Pangaea was the most recent supercontinent to have existed and the first to be reconstructed by geologists.
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PangeaMinusOne
Kindle_36% the supercontinent before pangea
peridotites
a dense, coarse-grained igneous rock consisting mostly of the minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg2+), reflecting the high proportions of magnesium-rich olivine, with appreciable iron. Peridotite is derived from the Earth's mantle, either as solid blocks and fragments, or as crystals accumulated from magmas that formed in the mantle. The compositions of peridotites from these layered igneous complexes vary widely, reflecting the relative proportions of pyroxenes, chromite, plagioclase, and amphibole. Peridotite is the dominant rock of the upper part of the Earth's mantle.
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Permian
a geologic period and system which spans 47 million years from the end of the Carboniferous Period 298.9 mya, to the beginning of the Triassic period 251.902 Mya. It is the last period of the Paleozoic era; the following Triassic period belongs to the Mesozoic era. The concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the region of Perm in Russia.

The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals, turtles, lepidosaurs, and archosaurs. The world at the time was dominated by two continents known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, which could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors.

The Permian (along with the Paleozoic) ended with the Permian–Triassic extinction event, the largest mass extinction in Earth's history, in which nearly 96% of marine species and 70% of terrestrial species died out. It would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian–Triassic extinction event was protracted; on land, ecosystems took 30 million years to recover.
See geoPeriods table
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phyllite
a type of foliated metamorphic rock created from slate that is further metamorphosed so that very fine grained white mica achieves a preferred orientation. It is primarily composed of quartz, sericite mica, and chlorite.
pillow basalts
When basalt erupts underwater or flows into the sea, contact with the water quenches the surface and the lava forms a distinctive pillow shape, through which the hot lava breaks to form another pillow.
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pillow lava
placer
sandbank, pleasure. Spanish.
plagiogranite
plate tectonics
Pleistocene

See geoPeriods table
Pliocene

See geoPeriods table
pluton
giant, upwelling 'balloons' of molten rock.
Pull-A-Part basin
pyroxene
a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes have the general formula XY(Si,Al)2O6, where X represents calcium, sodium, iron (II) or magnesium and more rarely zinc, manganese or lithium, and Y represents ions of smaller size, such as chromium, aluminium, iron (III), magnesium, cobalt, manganese, scandium, titanium, vanadium or even iron (II).

The name pyroxene is derived from the Ancient Greek words for fire and stranger. Pyroxenes were so named because of their presence in volcanic lavas, where they are sometimes seen as crystals embedded in volcanic glass; it was assumed they were impurities in the glass, hence the name "fire strangers".

The upper mantle of Earth is composed mainly of olivine and pyroxene. Pyroxene and feldspar are the major minerals in basalt and gabbro.
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quartz monzonite
quartz
silicon dioxide
quartzite
regolith
a layer of loose, heterogeneous superficial deposits covering solid rock. It includes dust, soil, broken rock, and other related materials and is present on Earth, the Moon, Mars, some asteroids, and other terrestrial planets and moons.
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rhyolite tuff
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Rodinia
1100 mya to 633 mya. Formed at c. 1.23 Ga by accretion and collision of fragments produced by breakup of an older supercontinent, Columbia, assembled by global-scale 2.0–1.8 Ga collisional events.
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San Andreas fault
"a water store", Kindle_79%
sandstone
turn into quartzites
schist
a medium-grade metamorphic rock. Schist has medium to large, flat, sheet-like grains in a preferred orientation (nearby grains are roughly parallel).
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serpentine
greenish rock. from near mantle.
shale
a fine-grained, clastic sedimentary rock, composed of mud that is a mix of flakes of clay minerals and tiny fragments (silt-sized particles) of other minerals, especially quartz and calcite. Shale is characterized by breaks along thin laminae or parallel layering or bedding less than one centimeter in thickness, called fissility. It is the most common sedimentary rock.
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Sierra Nevada mountains
silica
SiO2, silicon, oxygen
silicate
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silicate minerals
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siliceous ooze
The biogenic sediment that covers large areas of the deep ocean floor, and which contains the silicon skeletal remains of diatoms, silicoflagellates, and radiolarians. ("ooze" was used in the book "Assembling California") Chert is from siliceous ooze(?).
sluice
Smartville Block
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Sonomia
island arc. The Sonomia Terrane is a geologic crustal block known as a "terrane" whose remnants today lie in northwest Nevada. The terrane acquired its name from the Sonoma Range in that region. The Sonomia Terrane is associated with the Golconda Thrust, a structure named for its proximity to the town of Golconda, Nevada. The Sonoma orogeny was caused by the accretion of the Sonomia microcontinent onto western North America during the mid-Triassic. wikip
spreading center
wikip, 'mid-ocean ridge'
Scablands
Channeled Scablands at one time were a relatively barren and soil-free region of interconnected relict and dry flood channels, coulees and cataracts eroded into Palouse loess and the typically flat-lying basalt flows that remain after cataclysmic floods within the southeastern part of the U.S. state of Washington. The channeled scablands were scoured by more than 40 cataclysmic floods during the Last Glacial Maximum and innumerable older cataclysmic floods over the last two million years. These cataclysmic floods were repeatedly unleashed when a large glacial lake repeatedly drained and swept across eastern Washington and down the Columbia River Plateau during the Pleistocene epoch. The last of the cataclysmic floods occurred between 18,200 and 14,000 years ago.
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Strath Terrace ( Fluvial terrace )
Fluvial terraces are elongated terraces that flank the sides of floodplains and fluvial valleys all over the world. They consist of a relatively level strip of land, called a “tread,” separated from either an adjacent floodplain, other fluvial terraces, or uplands by distinctly steeper strips of land called “risers.” These terraces lie parallel to and above the river channel and its floodplain. Because of the manner in which they form, fluvial terraces are underlain by fluvial sediments of highly variable thickness.
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stratigraphic sequence
from older theories
stratigraphy
pre-tectonics means of describing
strike-slip faults
The 2 sides move in opposite directions, like like the San Andreas fault.
subduction
suture
line where 2 land masses (plates?) seem sewn together.
syncline
terrane (fragment of crust)
is a fragment of crustal material formed on, or broken off from, one tectonic plate and accreted or "sutured" to crust lying on another plate. (Its homophone, "Terrain", means topographical relief).
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Tertiary
the geologic period from 66 million to 2.6 million years ago, a timespan that occurs between the Mesozoic Era and the Quaternary. wikip
See geoPeriods table
Tethys
a Mesozoic-era ocean between the continents of Gondwana and Laurasia.

It's also a name from Greek mythology and it's the name of one of Saturn's 62 moons.

Image and info from wikipedia.

Thalweg (route for water)
the line of lowest elevation within a valley or watercourse
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tidal channel
TBD
Tombolo (attached island)
a deposition landform in which an island is attached to the mainland by a narrow piece of land such as a spit or bar. Once attached, the island is then known as a tied island. A tombolo is a sandy isthmus.
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transform fault
many in ocean. San Andreas is a "modified transform fault".
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Triassic (before Jurassic)
earliest of 3 parts of Mesozoic Era.
See geoPeriods table
umber
brown or reddish brown earth pigments.
unconformities
xenolith (embedded frags)
rock frags which become embedded in a large rock.
Yardang (wind carved)
a streamlined protuberance carved from bedrock or any consolidated or semiconsolidated material by the dual action of wind abrasion by dust and sand, and deflation which is the removal of loose material by wind turbulence. Yardangs become elongated features typically three or more times longer than wide, and when viewed from above, resemble the hull of a boat.
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crust
lithosphere
asthenosphere
mantle (orange)
mantle (yellow)
outer core, liquid
inner core, solid

Heat flow is conductive from the inner core to the outer and from the crust into the atmosphere. Every other layer has some level of convective flow.





(a subset of) Wikipedia's Geologic Periods table

I cut off the periods older than 1 billion years; see wikip page for the full (and updated) table.