{ "$schema": "https://pointcast.xyz/geology.json", "name": "Geology — UES Track 08", "description": "The ground beneath the marine layer. Stratigraphic column for the 25-mile radius, the Newport-Inglewood Fault, three scales of time, twelve stones paired to Nouns, four field walks, three practices, glossary, and citations.", "generatedAt": "2026-07-27T04:44:54.911Z", "human": "https://pointcast.xyz/geology", "parent": "https://pointcast.xyz/university-of-el-segundo", "radius": { "name": "PointCast participation radius", "label": "25-mile local layer", "radiusMiles": 25, "radiusMeters": 40234, "anchor": { "name": "El Segundo, California, USA", "coords": { "latitude": 33.9194, "longitude": -118.4088 } }, "policy": "Start with the 25-mile Beacon radius for anything that needs people to meet, trade, play, teach, or bring something physical. Keep the 100-mile Local lens for broadcast, stations, and broader Southern California context." }, "principles": [ "The ground is older than the meditation. Sit on it accordingly.", "A stone’s metaphysical property is half its mineralogy and half the human trying to listen. Honor both halves.", "Local stones over imported crystals. Sand from El Porto outranks rose quartz from Madagascar for our purposes.", "Take only photographs. Leave only ledger entries. The radius is a museum without a gift shop.", "The Newport–Inglewood Fault runs through the radius. The ground is not metaphor.", "Time is the rare material here. A bench is a year of stewardship; a granite ridge is one hundred million; a Banded Iron Formation is two and a half billion.", "Nouns are stones too. Each one we pair with a mineral is a way of saying: this object has properties we are listening for." ], "localStratigraphy": [ { "rank": 1, "formation": "Anthropocene fill", "ageRange": "~1900 CE – present", "thickness": "0–40 ft locally", "rockType": "Concrete, asphalt, fly ash, plastic, drilled-mud cement.", "observableEvidence": "Every sidewalk. The LAX runway aprons. The Hyperion outfall pipe trace. Any oil-well pad you can see from the powerline easement.", "whereExposed": "Surface, everywhere developed." }, { "rank": 2, "formation": "Holocene beach sand and dune sand", "ageRange": "~11.7 Kya – present", "thickness": "5–40 ft", "rockType": "Loose quartz sand, well-sorted, modern aeolian and littoral.", "observableEvidence": "The active beach face at El Porto. The migrating dune lobe behind the LAX dunes preserve. Cross-bedding visible in any fresh shovel cut.", "whereExposed": "Beach face; back-dune fields below 30 ft elevation.", "citationKeys": [ "cgs-mb-dunes" ] }, { "rank": 3, "formation": "Manhattan Beach Sand Dunes (Late Pleistocene aeolian)", "ageRange": "~10 Kya – ~125 Kya", "thickness": "20–80 ft", "rockType": "Wind-deposited quartz sand, weakly cemented in places. The relict dunes our houses sit on.", "observableEvidence": "The 80–110 ft elevation surface that El Segundo sits on. The Imperial Avenue overlook. The El Segundo Blue butterfly’s habitat substrate.", "whereExposed": "Surface across most of El Segundo above 60 ft elevation.", "citationKeys": [ "cgs-mb-dunes", "usfws-es-blue" ] }, { "rank": 4, "formation": "Older Pleistocene marine terrace", "ageRange": "~125 Kya – ~500 Kya", "thickness": "10–60 ft", "rockType": "Marine sandstone and conglomerate, weakly cemented.", "observableEvidence": "The 100–200 ft bench surface inland of the dunes. Hilltop Park sits on it. Westchester bluffs cap the next terrace up.", "whereExposed": "Hilltop Park ridgeline; Westchester / Playa del Rey bluffs." }, { "rank": 5, "formation": "Pico Formation (Pliocene marine)", "ageRange": "~5.3 Mya – ~2.6 Mya", "thickness": "300–2,000 ft", "rockType": "Marine sandstone and siltstone, fossiliferous.", "observableEvidence": "Outcrops on the Palos Verdes Peninsula. Subsurface in oil-field cores at Inglewood and Wilmington.", "whereExposed": "Palos Verdes seacliffs; visible from El Porto on a clear day.", "citationKeys": [ "usgs-monterey" ] }, { "rank": 6, "formation": "Monterey Formation (Late Miocene siliceous shale)", "ageRange": "~17 Mya – ~5 Mya", "thickness": "1,000–6,000 ft", "rockType": "Diatomaceous shale, finely laminated. The source rock for most of California’s oil.", "observableEvidence": "The Inglewood Oil Field produces from this. Outcrop along Palos Verdes; finely banded white-and-grey cliffs at Point Dume up the coast.", "whereExposed": "Subsurface beneath El Segundo at 3,000–8,000 ft. Surface on Palos Verdes and at Point Dume.", "citationKeys": [ "usgs-monterey" ] }, { "rank": 7, "formation": "Topanga Group (Mid-Miocene volcaniclastic and marine)", "ageRange": "~17 Mya – ~14 Mya", "thickness": "500–2,500 ft", "rockType": "Volcanic tuff, sandstone, conglomerate. Marks the rifting that opened the LA Basin.", "observableEvidence": "Santa Monica Mountains exposures; subsurface in basin drill cores.", "whereExposed": "Santa Monica Mountains cuts along Topanga Canyon Boulevard." }, { "rank": 8, "formation": "Catalina Schist (basement)", "ageRange": "~115 Mya – ~85 Mya (peak metamorphism)", "thickness": "Many thousands of feet, base unknown", "rockType": "Blueschist–greenschist facies metamorphic rock. Subducted oceanic crust returned to the surface.", "observableEvidence": "The cliffs of Catalina Island. Drill-core fragments from deep wells beneath the LA Basin.", "whereExposed": "Catalina Island cliffs; offshore wells.", "citationKeys": [ "usgs-catalina" ] } ], "fault": { "name": "Newport–Inglewood Fault Zone", "type": "Right-lateral strike-slip with a transpressional component", "length": "~75 km on land (Beverly Hills to Newport Beach), continuing offshore as the Newport–Inglewood–Rose Canyon system to San Diego.", "slipRate": "~0.5–1.0 mm per year (slow but persistent).", "trace": "Through the radius the fault trends NW–SE: under Beverly Hills, through Inglewood and Baldwin Hills, beneath the Sepulveda corridor in El Segundo, and out under the seafloor southwest of Long Beach.", "notableEarthquakes": [ "1933 Long Beach earthquake — magnitude 6.4, 120 deaths, the event that gave California school buildings the Field Act.", "1920 Inglewood earthquake — magnitude ~4.9, the first instrumental hint of a fault no one had named yet." ], "whyItMatters": "The fault is the reason the LA Basin has hills (Baldwin Hills, Signal Hill, Bolsa Chica) and the reason it has oil fields (the same uplifts trap hydrocarbons). For our purposes: the ground under our 25-mile radius is not metaphor. It moves a millimeter a year, and every century or so it remembers it can move a meter.", "citationKeys": [ "usgs-nif", "cgs-1933" ] }, "scales": [ { "level": "local", "label": "25-mile radius", "span": "Last ~2 million years; visible from a bench.", "features": [ "Manhattan Beach Sand Dunes formation — Late Pleistocene aeolian, the relict dunes most houses inside the radius sit on.", "Ballona Wetlands estuarine sediment — the Los Angeles River’s memory before LAX redirected the basin.", "Palos Verdes uplifted marine terraces — visible from El Porto on a clear day; each terrace is a former sea level raised by tectonic uplift faster than the ocean could erode it.", "LAX bluffs and Westchester bluffs — Pleistocene sandstone, slowly eroding into the Pacific at measurable rates.", "Newport–Inglewood Fault — runs NW–SE through the radius; the ground is not metaphor.", "Inglewood Oil Field — Pliocene–Miocene reservoirs over the same fault uplift, producing since 1924.", "El Segundo Blue butterfly habitat — federally endangered relict-dune endemic; one of the radius’s clearest geology-coupled life forms." ] }, { "level": "national", "label": "California", "span": "Last ~250 million years; visible from a road trip.", "features": [ "Sierra Nevada batholith — granite plutons assembled over ~100 million years, peak emplacement Cretaceous (~100–85 Mya).", "Coast Ranges Franciscan mélange — accreted seafloor and ocean-island fragments scraped off a subducting slab during Jurassic–Cretaceous time.", "San Andreas Fault — Pacific Plate sliding north against the North American Plate at ~35 mm per year.", "Channel Islands — drowned summits of the Transverse Ranges; sea-level change is the editor.", "Mojave volcanic field — Pisgah, Amboy, the lavas that did not become Mount St. Helens.", "Salton Trough — the present-day spreading center where the Gulf of California is opening into the continent." ] }, { "level": "global", "label": "The Earth and its company", "span": "4.54 billion years; visible from orbit and from imagination.", "features": [ "Pacific Ring of Fire — the subduction trench-and-arc system El Segundo is one quiet edge of.", "Banded Iron Formations (~2.5 to 1.85 Bya) — Earth’s Great Oxidation Event written in rust layers.", "Pangaea breakup (~200 Mya) — the moment the Atlantic began.", "KPg boundary (~66 Mya) — the iridium clay that records the day the dinosaurs lost.", "The Anthropocene strata (~1950 onward) — plastic, fly ash, concrete, and Cs-137 in sediment cores.", "Mars hematite plains — geology continues without us, on a planet we are sending rovers to." ] } ], "deepTime": [ { "yearsAgo": "4.54 Bya", "event": "Earth accretes from the solar nebula.", "rockEvidence": "Zircon crystals from the Jack Hills, Australia (4.4 Bya) — the oldest known Earth material." }, { "yearsAgo": "3.5 Bya", "event": "Earliest unambiguous microbial life.", "rockEvidence": "Stromatolites in the Strelley Pool Formation, Australia." }, { "yearsAgo": "2.45 Bya", "event": "Great Oxidation Event — atmosphere becomes breathable.", "rockEvidence": "Banded Iron Formations; red beds appear in the geologic record." }, { "yearsAgo": "541 Mya", "event": "Cambrian Explosion — most modern animal phyla appear.", "rockEvidence": "Burgess Shale (508 Mya), Chengjiang biota." }, { "yearsAgo": "252 Mya", "event": "Permian–Triassic mass extinction — the worst one. ~96% of marine species gone.", "rockEvidence": "Boundary clay; Siberian Traps flood basalts as the likely trigger." }, { "yearsAgo": "66 Mya", "event": "Cretaceous–Paleogene mass extinction — non-avian dinosaurs gone.", "rockEvidence": "Iridium clay layer worldwide; Chicxulub crater on the Yucatán." }, { "yearsAgo": "11.7 Kya", "event": "Holocene begins. Glaciers retreat. Sea level rises ~120 m to current position.", "rockEvidence": "Modern beach sand at El Porto. Drowned shorelines on the continental shelf." }, { "yearsAgo": "1950 CE", "event": "Anthropocene marker level (proposed). Cs-137 from atmospheric nuclear testing appears in every sediment core on Earth.", "rockEvidence": "Bomb-spike Cs-137 layer in lake sediments globally; plastic begins appearing in marine cores." } ], "stones": [ { "slug": "sand-silica", "name": "Sand · silica", "mineralogy": "Wind- and wave-sorted quartz grains, ~99% SiO₂. The Manhattan Beach Sand Dunes formation is Late Pleistocene to Holocene aeolian, draped over older marine terraces.", "scale": "local", "whereToFind": "El Porto sand at low tide. Imperial Avenue dunes. The ground under your house if you live in El Segundo. The LAX dunes preserve, where the same sand is federally protected habitat.", "metaphysicalProperty": "Amplification and clarity. The substrate everything else is built on. A patient material that became a circuit board only after we learned to see what it was.", "nounSeed": 137, "pairingNote": "Noun 137 carries the original PointCast mainnet smoke-test mint. The mineral and the receipt rhyme.", "citationKeys": [ "cgs-mb-dunes", "usfws-es-blue" ], "nounArt": "https://noun.pics/137.svg" }, { "slug": "magnetite-beach", "name": "Magnetite black sand", "mineralogy": "Heavy mineral concentrate — magnetite (Fe₃O₄), ilmenite (FeTiO₃), zircon, garnet — wave-sorted into dark bands by density. A magnet picks them up; this is the observable test.", "scale": "local", "whereToFind": "El Porto beach face on the swash zone after winter storms. The dark bands two to six inches wide where the sand changes color.", "metaphysicalProperty": "Polarity and orientation. A pocket-magnet works on these grains; a compass needle is just a slower magnetite. The Earth’s magnetic field has reversed itself ~183 times in the last 83 million years and the rocks remember.", "nounSeed": 99, "pairingNote": "Iron-glasses Noun. A mineral that orients toward the pole.", "citationKeys": [ "usgs-heavy-mineral" ], "nounArt": "https://noun.pics/99.svg" }, { "slug": "monterey-shale", "name": "Monterey Shale", "mineralogy": "Late Miocene siliceous shale, ~17–5 million years old. Diatomaceous, finely laminated. The source rock for the Inglewood Oil Field and most California crude.", "scale": "local", "whereToFind": "Subsurface beneath El Segundo, ~3,000–8,000 feet down. Surface exposures along Palos Verdes cliffs and at Point Dume. The Inglewood Oil Field on the Baldwin Hills produces from this and the overlying Pico.", "metaphysicalProperty": "Patience. The plankton that made this rock died for 12 million years to become an oil field. Every car here drinks ancient sunlight.", "nounSeed": 444, "pairingNote": "Pale-grey palette. The Noun as fossilized diatom.", "citationKeys": [ "usgs-monterey" ], "nounArt": "https://noun.pics/444.svg" }, { "slug": "catalina-blueschist", "name": "Catalina blueschist", "mineralogy": "Glaucophane-bearing schist, formed under high pressure and low temperature ~115 million years ago in a Late Cretaceous subduction zone. The metamorphic basement under the LA Basin.", "scale": "local", "whereToFind": "The cliffs of Catalina Island. In offshore drill cores beneath the LA basin sediments. The thing under everything, here.", "metaphysicalProperty": "Compression. A rock that was made by being squeezed under twenty miles of overlying crust. The deepest local stone is the one that shows up to therapy.", "nounSeed": 600, "pairingNote": "Cool blue-grey palette. A Noun under pressure.", "citationKeys": [ "usgs-catalina" ], "nounArt": "https://noun.pics/600.svg" }, { "slug": "obsidian", "name": "Obsidian", "mineralogy": "Volcanic glass — rhyolitic lava cooled too fast to crystallize. Conchoidal fracture; sharper than surgical steel at the edge.", "scale": "national", "whereToFind": "Glass Mountain (Modoc Plateau), Mono–Inyo Craters, the Coso volcanic field. None inside the radius — but obsidian arrowheads pulled from Ballona predate the city by 5,000 years.", "metaphysicalProperty": "Protection, grounding, scrying mirror. A stone that asks you to look at yourself before you ask it for anything.", "nounSeed": 7, "pairingNote": "Black-and-glass aesthetic. A mineral that already looks like an icon.", "nounArt": "https://noun.pics/7.svg" }, { "slug": "serpentine", "name": "Serpentine", "mineralogy": "Hydrated magnesium silicate, formed when oceanic crust gets dragged into a subduction zone and squeezed back up. California state rock since 1965.", "scale": "national", "whereToFind": "Coast Ranges throughout California — Marin headlands, New Idria, Diablo Range. Closest exposure to the radius is in the Santa Monica Mountains.", "metaphysicalProperty": "Kundalini and earth-energy. The rock that remembers being seafloor. Asbestos-bearing varieties are reminders that not every metaphysical property is benign.", "nounSeed": 42, "pairingNote": "Green-glasses Noun. The state rock under glasses tinted to match.", "citationKeys": [ "cgs-state-rock" ], "nounArt": "https://noun.pics/42.svg" }, { "slug": "granite", "name": "Granite", "mineralogy": "Coarse-grained intrusive — quartz, feldspar, mica. The Sierra Nevada batholith was assembled over ~100 million years from rising plutons, with peak emplacement during the Cretaceous (~100–85 Mya).", "scale": "national", "whereToFind": "Sierra Nevada (Yosemite, Mt. Whitney). The tile facade of the Bradbury Building. The countertop in someone’s kitchen on Whiting.", "metaphysicalProperty": "Stability and foundation. The mineral your civic buildings are clad in. A reminder that even bedrock was magma once.", "nounSeed": 256, "pairingNote": "Cool-grey palette. The Noun looks like it could clad a courthouse.", "citationKeys": [ "usgs-sierra" ], "nounArt": "https://noun.pics/256.svg" }, { "slug": "tourmaline", "name": "Tourmaline", "mineralogy": "Complex boron silicate. Pyroelectric — actually generates an electrical charge under temperature change. Comes in every color, including bicolor \"watermelon\" crystals.", "scale": "national", "whereToFind": "Pala District, San Diego County (~120 mi from El Segundo). The Stewart Mine has been open since the 1890s.", "metaphysicalProperty": "Protection and \"electric\" energy — uniquely, this metaphysical claim is partly literal. Tourmaline really does generate a surface charge under heating. The folklore got there first.", "nounSeed": 333, "pairingNote": "Pink/multi-color Noun. A stone that is its own rainbow.", "nounArt": "https://noun.pics/333.svg" }, { "slug": "glauconite", "name": "Glauconite (greensand)", "mineralogy": "Iron-potassium phyllosilicate. Forms only in slow-deposition marine settings; the green sand on a sea floor that was forgotten about for a million years. A reliable time-marker mineral.", "scale": "global", "whereToFind": "New Jersey marl pits (the Cretaceous shoreline). The Cretaceous–Paleogene boundary clay. Slow, deep, calm seafloors anywhere on Earth.", "metaphysicalProperty": "The patience of slow water. Greensand only forms where nothing is in a hurry. A stone that teaches the value of being briefly forgotten.", "nounSeed": 220, "pairingNote": "Sea-green palette. A Noun for the slow shelf.", "nounArt": "https://noun.pics/220.svg" }, { "slug": "labradorite", "name": "Labradorite", "mineralogy": "Plagioclase feldspar with internal lamellae that interfere with light to produce labradorescence — the flash of blue, gold, green, and copper.", "scale": "global", "whereToFind": "Labrador (the type locality). Madagascar. Finland. A few jewelry shops on Main Street that did not ask where the stone came from.", "metaphysicalProperty": "Aurora and transformation. The stone that hides until it is held at the right angle. A small reminder that some things only show themselves to attention.", "nounSeed": 512, "pairingNote": "Iridescent palette. A Noun that looks different the longer you look.", "nounArt": "https://noun.pics/512.svg" }, { "slug": "hematite", "name": "Hematite", "mineralogy": "Iron oxide (Fe₂O₃). Earth’s Banded Iron Formations were laid down 2.5 to 1.85 billion years ago when cyanobacteria first oxygenated the ocean — the stone that records the Great Oxidation Event.", "scale": "global", "whereToFind": "Minnesota Iron Range, Western Australia’s Hamersley basin, Brazil’s Carajás. And on Mars, where it gives the planet its color.", "metaphysicalProperty": "Grounding and blood-iron resonance. The mineral whose name shares a root with hemoglobin. The first time the Earth nearly killed itself with its own success was an iron oxide event.", "nounSeed": 666, "pairingNote": "Red/dark palette. Iron and rust as a Noun.", "citationKeys": [ "usgs-bif" ], "nounArt": "https://noun.pics/666.svg" }, { "slug": "calcite", "name": "Calcite", "mineralogy": "Calcium carbonate (CaCO₃). Limestone is mostly biogenic — fossilized plankton and reef. Cement (the binder under LAX runways) is calcined limestone.", "scale": "local", "whereToFind": "Every concrete sidewalk in El Segundo. Every coastline cliff with white bands. The mineral your bones rhyme with but are not made of.", "metaphysicalProperty": "Clearing and light amplification. Iceland-spar calcite literally doubles whatever you look at through it (double refraction). A stone that taught optics to physicists.", "nounSeed": 888, "pairingNote": "White/light palette. The Noun as plankton-fossil archive.", "nounArt": "https://noun.pics/888.svg" } ], "geologyCoupledLife": [ { "name": "El Segundo Blue butterfly", "latin": "Euphilotes battoides allyni", "status": "Federally endangered (1976).", "whyHere": "Endemic to the El Segundo Sand Dunes — the Manhattan Beach Sand Dunes formation. Larval host plant is seacliff buckwheat (Eriogonum parvifolium). The largest remaining population lives on a ~285-acre preserve at LAX. The butterfly exists because the dune does.", "citationKeys": [ "usfws-es-blue" ] } ], "fieldWalks": [ { "slug": "el-porto-sand-layers", "title": "Read the sand layers", "place": "El Porto Beach at low tide", "read": "Look for heavy-mineral concentrations — the dark bands of magnetite and ilmenite the waves sort by density. Read the cross-bedding in the dune toe.", "bring": "A small magnet, a phone camera, and a sharpened sense of patience.", "take": "A photograph of one dark band held against the magnet.", "photoPrompts": [ "A close-up of a dark band where the sand changes color, magnet held nearby.", "A wide shot showing the swash zone with at least three distinct sand-color stripes.", "A grain-level macro: tilt the camera until you can see individual quartz vs. dark grains." ] }, { "slug": "imperial-pleistocene-dune", "title": "Stand on a Pleistocene dune", "place": "Imperial Avenue overlook, top of the dunes", "read": "You are standing on aeolian sand that arrived ~10,000 to 125,000 years ago. The Pacific was twenty to thirty miles further out at the Last Glacial Maximum.", "bring": "A jacket. The marine layer rolls in cold.", "take": "A note about what you imagine the view looked like at the LGM, with the shoreline somewhere off the horizon.", "photoPrompts": [ "The view due west, panoramic, ideally with the marine layer present.", "The dune surface at your feet, showing color and grain.", "A reference shot of a known landmark for scale (the airport tower, a refinery flare)." ] }, { "slug": "palos-verdes-uplift", "title": "Read the Palos Verdes uplift", "place": "Hilltop Park, looking south toward the peninsula", "read": "Each terrace on the peninsula is a former sea level, raised by tectonic uplift faster than the ocean could erode it. The lowest terrace is youngest; count them upward.", "bring": "Binoculars if you have them. A clear day if you can pick one.", "take": "A count of distinct terrace surfaces you can see, with a photo for each.", "photoPrompts": [ "A horizon-line panorama south from Hilltop showing the peninsula stair-step.", "A zoom on the most distinct single terrace edge.", "The view straight down at the bench surface you are standing on (also a Pleistocene terrace)." ] }, { "slug": "vista-del-mar-cliff-retreat", "title": "See active sea-cliff retreat", "place": "Vista del Mar bluffs, walking south from Dockweiler", "read": "The bluff face is losing inches to feet per year. Notice fresh exposures, slumped vegetation, the line where the road has been moved inland over decades.", "bring": "Sturdy shoes; do not approach the edge.", "take": "A photograph of one fresh exposure for the field-walk log.", "photoPrompts": [ "A fresh exposure showing the bedding and color of the Pleistocene sandstone.", "A slump scarp or cracked vegetation line where the bluff is actively failing.", "The road centerline with reference to the bluff edge for a future re-photograph." ] } ], "practices": [ { "name": "Stone in pocket", "detail": "Pick a stone from a place inside the radius. Carry it for one week. Return it to within ten feet of where you found it. Notice what changed in your attention." }, { "name": "Sit with stone", "detail": "For one Marine Layer week, sit your daily 10 minutes with a single named stone in your hand. Do not think about it. Just hold it." }, { "name": "Read the layer", "detail": "On any cliff, sand bank, or road cut inside the radius, spend ten minutes reading the visible stratigraphy as if it were a paragraph written by time. Younger above, older below." } ], "glossary": [ { "term": "Aeolian", "def": "Wind-deposited. Sand dunes are aeolian sediment." }, { "term": "Batholith", "def": "A very large mass of igneous rock formed underground from cooling magma. The Sierra Nevada is one." }, { "term": "Conchoidal fracture", "def": "A curved, shell-like break pattern characteristic of obsidian, flint, and chert." }, { "term": "Cross-bedding", "def": "Internal layers in a sediment that are tilted relative to the main bedding — a record of past wind or current direction." }, { "term": "Diatomaceous", "def": "Made of the silica skeletons of single-celled algae called diatoms. Monterey shale is diatomaceous." }, { "term": "Felsic", "def": "Light-colored igneous rock rich in feldspar and silica. Granite is felsic." }, { "term": "Holocene", "def": "The current geological epoch, beginning ~11,700 years ago at the end of the last glaciation." }, { "term": "Mélange", "def": "A chaotic mixture of rock fragments in a finer matrix, typical of accreted material in subduction zones." }, { "term": "Pleistocene", "def": "The Ice Age epoch from ~2.6 million to 11,700 years ago. The Manhattan Beach Sand Dunes formation is Late Pleistocene." }, { "term": "Pyroelectric", "def": "A material that develops a temporary electric voltage when it is heated or cooled. Tourmaline is pyroelectric." }, { "term": "Stratigraphy", "def": "The arrangement and study of rock layers. Younger layers above, older below, unless tectonics has flipped them." }, { "term": "Subduction", "def": "The process where one tectonic plate slides beneath another. The reason there is a Pacific Ring of Fire." } ], "citations": [ { "key": "cgs-mb-dunes", "source": "California Geological Survey — South Bay surficial geology and Manhattan Beach Sand Dunes formation." }, { "key": "cgs-state-rock", "source": "California state rock designation: serpentine (Government Code §425.2, adopted 1965)." }, { "key": "cgs-1933", "source": "California Geological Survey reports on the 1933 Long Beach earthquake (M 6.4) and the Field Act response." }, { "key": "usgs-monterey", "source": "USGS — Monterey Formation: source rock geology, age range ~17–5 Mya." }, { "key": "usgs-catalina", "source": "USGS / NOAA — Catalina Schist: late Cretaceous–Paleogene blueschist basement of the inner California Borderland." }, { "key": "usgs-sierra", "source": "USGS — Sierra Nevada batholith assembly, peak emplacement during Cretaceous arc magmatism." }, { "key": "usgs-bif", "source": "USGS / GSA — Banded Iron Formations and the Great Oxidation Event (~2.45 Bya)." }, { "key": "usgs-nif", "source": "USGS Quaternary Fault and Fold Database — Newport–Inglewood Fault Zone parameters." }, { "key": "usgs-heavy-mineral", "source": "USGS Open-File Report — Heavy-mineral concentrations in Southern California beach sands." }, { "key": "usfws-es-blue", "source": "U.S. Fish & Wildlife Service — El Segundo Blue butterfly listing and recovery plan; LAX dunes preserve management." } ], "related": { "marineLayer": "https://pointcast.xyz/marine-layer", "commons": "https://pointcast.xyz/commons", "civicLayer": "https://pointcast.xyz/civic-layer", "ues": "https://pointcast.xyz/university-of-el-segundo" }, "nounsAttribution": "Nouns artwork at noun.pics is CC0. Seeds 0-1199 match the original Nouns FA2 supply." }