File:Chalk ("Upper Chalk" Formation, Upper Cretaceous; White Cliffs of Dover, England, southern Britain).jpg
Algfail (864 × 715 pikslit, faili suurus: 789 KB, MIME tüüp: image/jpeg)
Pealdised
Lühikirjeldus
[muuda]KirjeldusChalk ("Upper Chalk" Formation, Upper Cretaceous; White Cliffs of Dover, England, southern Britain).jpg |
English: Chalk from the Cretaceous of Britain.
Sedimentary rocks form by the solidification of loose sediments. Loose sediments become hard rocks by the processes of deposition, burial, compaction, dewatering, and cementation. There are three categories of sedimentary rocks: 1) Siliciclastic sedimentary rocks form by the solidification of sediments produced by weathering & erosion of any previously existing rocks. 2) Biogenic sedimentary rocks form by the solidification of sediments that were once-living organisms (plants, animals, micro-organisms). 3) Chemical sedimentary rocks form by the solidification of sediments formed by inorganic chemical reactions. Most sedimentary rocks have a clastic texture, but some are crystalline. Limestone is a common biogenic sedimentary rock composed of the mineral calcite (CaCO3), which bubbles in acid. Many geologically young limestones are composed of aragonite (also CaCO3). Numerous varieties of limestone exist (e.g., fine-grained limestone/micritic limestone/lime mudstone, coquina, chalk, wackestone, packstone, grainstone, rudstone, rubblestone, coralstone, calcarenite, calcisiltite, calcilutite, calcirudite, floatstone, boundstone, framestone, oolitic limestone, oncolitic limestone, etc.). Most limestones represent deposition in ancient warm, shallow ocean environments. Chalk is distinctive variety of limestone that is soft, whitish, and powdery. Chalk is composed of calcite (CaCO3), and will bubble in acid. The most spectacular chalk locality on Earth is the White Cliffs of Dover (farm1.static.flickr.com/119/290719612_5a27cbaf61.jpg), along the southern shores of Britain. The rocks there are Cretaceous in age (“creta” means “chalk”). Chalk is a biogenic sedimentary rock, but it is not obvious how this white powdery material represents the remains of once-living organisms. When examined under a scanning electron microscope, chalk powder is seen to be composed of immense numbers of exceedingly small microfossils, principally coccoliths (www.soes.soton.ac.uk/staff/tt/eh/pics/lith2.gif). Coccoliths are calcitic plates that once covered a living cell (upload.wikimedia.org/wikipedia/commons/d/d9/Emiliania_hux...). The cell was an entire organism called a coccolithophorid (Kingdom Protista, Phylum Chrysophyta, Class Coccolithophorida). Coccolithophorids are unicellular, photosynthetic organisms. They are often called “algae”, but they’re better called photosynthetic protists. When they die, the cell degrades, and the numerous hard calcitic plates covering the cell fall to the seafloor. Chalk generally forms in moderately deep marine environments (but not in the deepest ocean depths), where high numbers of coccolith plates can accumulate as sediments, without calcite dissolution, and undiluted by muddy or sandy sediments washed in from the continents. |
Kuupäev | |
Allikas | https://www.flickr.com/photos/jsjgeology/16610898008/ |
Autor | James St. John |
Litsents
[muuda]- Tohid:
- jagada – teost kopeerida, levitada ja edastada
- kohandada – valmistada muudetud teoseid
- Järgmistel tingimustel:
- omistamine – Pead materjali sobival viisil autorile omistama, tooma ära litsentsi lingi ja märkima ära, kas on tehtud muudatusi. Sobib, kui teed seda mõistlikul viisil, kuid seejuures ei tohi jääda muljet, et litsentsiandja tõstab esile sind või seda, et sina materjali kasutad.
James St. John postitas selle pildi algselt saidile Flickr. Robot FlickreviewR 2 vaatas selle pildi üle ja kinnitas, et see oli saadaval litsentsi cc-by-2.0 all. Vaadatud: 18. märts 2021 |
18. märts 2021
Faili ajalugu
Klõpsa kuupäeva ja kellaaega, et näha sel ajahetkel kasutusel olnud failiversiooni.
Kuupäev/kellaaeg | Pisipilt | Mõõtmed | Kasutaja | Kommentaar | |
---|---|---|---|---|---|
viimane | 18. märts 2021, kell 19:17 | 864 × 715 (789 KB) | Annawood2 (arutelu | kaastöö) | Uploaded a work by James St. John from https://www.flickr.com/photos/jsjgeology/16610898008/ with UploadWizard |
Sa ei saa seda faili üle kirjutada.
Faili kasutus
Seda faili ei kasuta ükski lehekülg.
Globaalne failikasutus
Järgmised muud vikid kasutavad seda faili:
- Faili kasutus vikis el.wikipedia.org
- Faili kasutus vikis en.wikipedia.org
- Faili kasutus vikis en.wiktionary.org
- алтан
- минерал
- туус
- Reconstruction:Proto-Turkic/tiāĺ
- көмүс
- тимир
- Reconstruction:Proto-Turkic/kümüĺ
- Reconstruction:Proto-Turkic/altun
- таас
- Reconstruction:Proto-Turkic/kömür
- Reconstruction:Proto-Turkic/temür
- Reconstruction:Proto-Turkic/bakïr
- Template:table:minerals/trk-pro
- Reconstruction:Proto-Turkic/korguĺčïn
- Template:table:minerals/sah
- үрүҥ көмүс
- кыһыл көмүс
- миэл
- көмөр
- сибиниэс
- Template:table:minerals/sla-pro
- Reconstruction:Proto-Turkic/tūŕ
- Reconstruction:Proto-Turkic/tūč
- Faili kasutus vikis et.wikipedia.org
- Faili kasutus vikis kw.wikipedia.org
- Faili kasutus vikis mg.wiktionary.org
- Faili kasutus vikis sr.wikipedia.org
- Faili kasutus vikis uz.wikipedia.org
- Faili kasutus vikis zh-yue.wikipedia.org
- Faili kasutus vikis zh.wikipedia.org
- Faili kasutus vikis zh.wiktionary.org
Metaandmed
See fail sisaldab lisateavet, mille on tõenäoliselt lisanud digikaamera või skanner.
Kui faili on rakendustarkvaraga töödeldud, võib osa andmeid olla muudetud või täielikult eemaldatud.
Pikslite koosseis | RGB |
---|---|
Orientatsioon | Normaalne |
Horisontaalne eraldus | 550 dpi |
Vertikaalne eraldus | 550 dpi |
Kasutatud tarkvara | Adobe Photoshop CS2 Macintosh |
Faili muutmise kuupäev ja kellaaeg | 12. märts 2015, kell 21:14 |
Värviruum | Kalibreerimata |
Pildi laius | 864 px |
Pildi kõrgus | 715 px |
Digiteerimise kuupäev ja kellaaeg | 12. märts 2015, kell 17:14 |
Metaandmete viimane muutmisaeg | 12. märts 2015, kell 17:14 |