Discover and read the best of Twitter Threads about #geology

Most recents (24)

Poetry host Larissa Reid @Ammonites_Stars has been fascinated with geology since she was a child. She spent six years volunteering with the Scottish Geodiversity Forum (now @scottishgeology) and founded and runs the biennial Hugh Miller Writing Competition. #TopTweetTuesday
Poetry by our host from Scotland, Larissa Reid @Ammonites_Stars #time #memory #landscape #nature #poetry #scottishpoetry #geology 💎

‘I slip from dream to real to back’
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I've never quite been the same since I learned about trovants. These are rocks, actual rocks, that not only 'grow' but MULTIPLY.
The most famous example can be found in the tiny village of Costeşti in Valcea County, Romania. Known locally as the 'living stones' they have been the backdrop to folktales for millennia.
Indeed they have been there much longer than people, coming into existence due to a series of earthquakes some 6 million years ago.
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Travelling through #India you can't miss such boulder heaps...

Think of Hampi's ruins (below) or Sravanabelagola (Karnataka), or Mt Abu (Rajasthan)?

#DidYouKnow, such isolated hill/ridge features that jut out from the surrounding plains are called #inselbergs?

#Geo thread/ Geology: inselberg formation at Hampi, Karnataka, India
Derived from German words meaning 'island mountain', #inselbergs are residual features that form across climatic zones.

Yet are most abundant in tropical regions with granite-gneiss outcrops, like those on the cratons across India, as also in the zones marked BCG, CGC, and SGT. Map in the publication, The Indian Peninsula: Geomorphic Lan
Debates rage on how #inselbergs formed, yet most concede they are the result of weathering (breaking down of rocks at site) and erosion (transport of weathered material).

In #India, insolation (heat from sun's rays), rainwater, and rivers have shaped landscapes for millennia. Hampi's boulder inselbergs with the river Tungabhadra snakin
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Morning everyone! I’m Katy and I’m going to tweet about #archaeology, #geology and #landscape. But mostly, about #sarsen stone in the county of Wiltshire, UK. Thank you to @lornarichardson and @James__Dixon for organising #PATC5 and for accepting this paper 0/16 The abstract for this Twitter paper: This paper takes one of my recent #DailySarsen tweets and tells a story of the sarsen stone depicted in that previously-tweeted photo. Much of my public archaeology happens out-of-doors. The frightening reality of a serious communicable disease that has no vaccine means it will be some time before I can once more welcome people into Sarsen Country. My small efforts to recover a sense of Sarsen Country digitally, with #DailySarsen, have been welcomed by friends old and new. So here is an elaboration of one of the tweets; I hope people will enjoy the tale.
During CV-19 lockdown and as long as distancing measures apply, my public archaeology landscape walks in #SarsenCountry are suspended. Groups trips for local/regional societies to visit places in Wiltshire (UK) where sarsen stones can be seen are off-limits #PATC5 #DailySarsen 1/ The title of my paper for the Public Archaeology Twitter Conference is ‘#DailySarsen, or, Walking hand-in-hand with human and non-human friends’. Katy Whitaker, University of Reading/Historic England @artefactual_KW
Sarsens are the large grey boulders making the familiar shapes of Stonehenge, and Avebury’s great circles. They’re in medieval church walls. They pave our streets and protect grass verges. Sites in southern England from Dorset to Norfolk make #SarsenCountry #PATC5 #DailySarsen 2/ A photograph of Stonehenge showing some of the tall upright grey sarsen stones capped by horizontal sarsen lintels. Two sarsens lie in the grass in the foreground.
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We love getting questions about #mining, #minerals and #geology! We were asked about historical #gold mining in #Brookfield, #QueensCounty. Check out this thread!

#nspoli #novascotia #nshistory #cbpoli #capebreton
@GordonWilsonLNS @BernJordanMP @RegionofQueens @LHNOWnews ImageImage
While there were several mines in the #Brookfield #Gold District, almost all the gold produced came from the Brookfield mine operated by Wilbur L. Libbey, which was discovered in 1885.
#nspoli #novascotia #nshistory #cbpoli #capebreton Image
In July 1886, it was acquired by John McGuire and some American associates known as the #Brookfield Milling Company. Under McGuire's management a considerable amount of ore was mined and hauled to #PleasantRiver, #Lunenburg County, for milling.
#nspoli #novascotia #nshistory Image
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We love getting questions about #mining, #minerals and #geology! We were asked about mining in Gays River:

#nspoli #cbpoli #novascotia #capebreton #nshistory @SeanFraserMP @LarryHarrisonPC #gold ImageImage
#Gold was discovered in Gays River, Colchester County, by George Gay and Berry Corbett on their adjoining farms in June 1862. Unfortunately, the pair initially charged exorbitant prices for accessing their properties which delayed prospecting and mining.
#nspoli #novascotia Image
In 1866, a small crusher was built but was not kept very busy. In 1869, a handful of tunnels and shafts were dug.
#nspoli #novascotia #nshistory Image
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Closed due to Covid AND road repair. Kasha-Katuwe is located on the Pajarito Plateau, at an elevation of 5700-6400 feet above sea level. Like most of the region, the volcanic activity that formed the Jemez Mountains sculpted the peculiar landscape. #geology #NewMexico #volcanic
The Jemez volcanic field has been active for the past 15 million years. It formed at the intersection of the Rio Grande rift and the Jemez lineament, an ancient northeast-trending fault line that has been a locus of volcanism for the last 10 million years.

#armchairtravel
The Valles Caldera is the 3rd largest super volcano in the U.S. It sits on top of an older caldera, the Toledo caldera, which may be on top of an older caldera. The calderas were formed during voluminous eruptions in the Jemez volcanic field 1.61 - 1.25 million years ago.
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Paris’ #NotreDame Cathedral caught fire one year ago today. Read this thread to learn why the stone used to build it came from #Paris' catacombs.
#nspoli #cbpoli #novascotia #capebreton #geology ImageImageImage
The limestone used to build Notre Dame formed 45 million years ago when Northern France was covered by a tropical sea. Limestone forms when bones/shells of sea creatures pile up and are compressed into rock.
#nspoli #cbpoli #novascotia #capebreton #geology #notredame Image
Limestone often has fossils in it as a result, like the clam in the picture below from #NotreDame.
Surface quarrying of limestone in the #Paris area started in the first century. Underground quarrying started in the 1300s and continued for centuries.
#nspoli #cbpoli #novascotia Image
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As people are tucking into Easter eggs today, here's a list of some of the *absolute worst* substitutes for chocolate eggs that #geology can offer you. Consider yourself warned.

A THREAD

(1/n)
Type: onion-skinned weathering of massive rocks (including sandstones and granites).

How: formed by weathering along spheroidal fracture planes within the rock mass

Why is bad: it's rock, so will break your teeth, and doesn't at all taste like chocolate

(2/n)
Type: concretions within sedimentary rock (often sandstones)

How: formed by precipitation of minerals around a central mass within sedimentary rock or soil

Why is bad: it's also rock, so will break your teeth, and doesn't at all taste like chocolate either

(3/n)
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Why does the granite at #PeggysCove have so many cracks?!
Check out this thread for the answer.

#nspoli #cbpoli #novascotia #capebreton @BernJordanMP @MattWhitman2020 @HughMacKayCSM @TourismNS @NS_Museum #nshistory #geology Image
The rocks at #PeggysCove began 470 million years ago as mud and sand in a deep ocean basin near ancient Africa. They built up and were eventually compacted into shale and sandstone.
#nspoli #cbpoli #novascotia #capebreton #nshistory #geology Image
As tectonic plate movement caused North Africa and North America to collide 400 million years ago, the shale and sandstone were squeezed between the two continents and heat and pressure transformed them into slate and quartzite.
#nspoli #cbpoli #novascotia #capebreton #nshistory Image
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Vamos con un hilo sobre imágenes de satélite de deltas (y alguna foto de la ISS)

🧵⤵️

Son imágenes espectaculares, ¿No os parece?

#InGeoSatelliteView #geología #geology #deltas #vistasatelite

Delta del río Mississippi 🇺🇸

Aporte de sedimentos

earthobservatory.nasa.gov/images/1257/mi… Image
Se estima que la costa ha avanzado , en el Sur de
Luisiana, hasta unos 80kms en los últimos
5.000 años.

earthobservatory.nasa.gov/images/145286/…

earthobservatory.nasa.gov/images/8103/mi… ImageImage
El mayor delta de Europa.

El río Volga en el Mar Caspio 🇷🇺

earthobservatory.nasa.gov/images/144231/… Image
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We love getting questions about #mining, #minerals and #geology! We were asked about #gemstones in #NovaScotia. Here’s our answer:

#nspoli #cbpoli #capebreton Image
Gemstones that are usually considered “precious stones” are diamonds, rubies, sapphires and emeralds. All other gemstones are considered “semi-precious” (i.e. agate, amber, amethyst, jade, pearl, etc.)
#nspoli #cbpoli #capebreton #NovaScotia Image
These definitions date from the 1800s and they are subjective, not scientific. There is not universal agreement with them, but we mention them to point out that there is usually a distinction made between precious and semi-precious stones.
#nspoli #cbpoli #capebreton #NovaScotia Image
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Re-watching some shows while #socialdistancing for #MarchBreak? We're chatting this week about some of our favourites that have great #geology or interesting stories behind their #filminglocations.
#nspoli #cbpoli #NovaScotia #CapeBreton #COVIDCanada #covid19 #COVID19NS ImageImageImageImage
#GameofThrones used #Iceland's #Thingvellir Park as the #BloodyGate. Its landscape is caused by the Eurasian and #NorthAmerican tectonic plates meeting there and pulling apart at a rate of 2 cms per year. This made a rift valley: low land between 2 separating continents.
#nspoli ImageImageImageImage
#MagheramorneQuarry, #NorthernIreland, is the set for #CastleBlack and #TheWall in #GameofThrones. The quarry wall is used as a backdrop and effects make it look huge.
The site's limestone was used to make cement. #NS has a limestone quarry and cement plant in Brookfield.
#nspoli ImageImage
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#VIRTUAL #GEOLOGY RESOURCES! I've taught an online geology course called Geology Goes Hollywood for years. The full course is on our campus LMS. I quickly threw together some websites with ready-to-steal materials that could help folks. Sorry the websites aren’t pretty. 1/
2/ There's the Earthquake Machine, a little block-and-slider widget that students can use to discover how hard it is to predict earthquakes. Video intro and online spreadsheet available: csun.edu/quake/eqmachin…
3/ Earthquake early warning simulator. Students design their own early warning network and test it out. Scroll to the bottom of the page for teaching resources.
csun.edu/quake/warning.…
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THREAD: #VIRTUAL #GEOLOGY RESOURCES! W/ so many schools online, thought it would be useful to help create list of free to use virtual field/sample resources for teaching geo online. Please respond w/ additional resources (description & link). Share widely! ADD MORE!
Virtual sand: This Excel file contains links to 150 gigapan images of sand samples. Students can zoom in to microscope level of magnification. Contains international examples. Courtesy of @callanbentley docs.google.com/spreadsheets/d…
Virtual fossils: Interactive 3D models of fossil specimens from collections of Paleontological Research Institution. Models housed on Sketchfab. Site includes exercises (mostly for K-12). Via @PRInstitution @PaleoDigAtlas digitalatlasofancientlife.org/vc/
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We love getting questions about mining, minerals and geology! We were asked about sand and fieldstone in the world-class #gypsum deposit in #Milford, Nova Scotia. This thread is our answer:

#nspoli #cbpoli #novascotia #capebreton #mining #geology @mmillershubie @SeanFraserMP ImageImage
327-342 million years ago, global sea levels rose and fell many times. This repeatedly flooded Nova Scotia with what we call the Windsor Sea. #NovaScotia was near the equator at that time so the sea also evaporated repeatedly in the tropical sun.
#nspoli #cbpoli #capebreton Image
This process gave us huge gypsum deposits because gypsum forms when water high in calcium and sulfate evaporates, leaving the calcium and sulfate behind as sediment. The sediment builds up and is eventually turned into gypsum rock by heat and pressure.
#nspoli #cbpoli #novascotia Image
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It's chilly today but nothing like during #SnowballEarth – a deep freeze that took place about 720-640 million years ago. Carbon dioxide levels plummeted, #Earth cooled and was mostly covered in ice.
#nspoli #cbpoli #Novascotia #capebreton #NS #CB Image
We know about #SnowballEarth thanks to #geology. Glacial deposits - rocks that were left by glaciers - indicate there were glaciers at the equator at that time. If there were glaciers in #Earth's warmest areas, there were probably glaciers everywhere.
#nspoli #cbpoli #Novascotia Image
#SnowballEarth likely ended because volcanic eruptions under the ice put CO2 back into the atmosphere and warmed earth again. This facilitated the #CambrianExplosion ~541 million years ago, in which complex animal life forms appeared on Earth for the 1st time.
#nspoli #cbpoli Image
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We love getting questions about #mining, #minerals and #geology! We were recently asked about #MicaHill in Cape Breton. Here’s our answer:

#nspoli #cbpoli #novascotia #capebreton #NS #CB #victoriacounty ImageImage
#MicaHill is likely #NovaScotia’s best deposit of mica. Test pits were sunk there in summer 1882 by the Scotian Mining Company which confirmed the presence of a large supply of good quality #mica.
#nspoli #cbpoli #novascotia #capebreton #NS #CB ImageImage
There are few records about the extraction took place on #MicaHill. This is not unusual. Many historical #NovaScotia mines/quarries have extensive documentation – and @NS_Energy_Mines plays an important role preserving them.
#nspoli #cbpoli #capebreton #NS #CB ImageImage
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We love getting questions about #mining, #minerals and #geology! We were recently asked about historical mining in #PortHood, #Inverness County. Here’s our answer:

#nspoli #cbpoli #NovaScotia #CapeBreton #NS #CB ImageImage
In the 1740s-1750s, a quarry on #PortHood Island was the main supply of finished/dressed sandstone for #FortressLouisbourg’s window and door casements. About 60 men worked there in summer and the stone was sent by barge through the #StraitofCanso to #Louisbourg.
#nspoli #cbpoli Image
Many historical #NovaScotia buildings, including the more important buildings at #Louisbourg, were made of stone that was considered somewhat unattractive (i.e. fieldstone or ironstone), so it was often fancied up with granite or sandstone trim.
#nspoli #cbpoli #CapeBreton #NS Image
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We love getting questions about #mining, #minerals and #geology! We were asked about the red soil and sand at #CabotsLanding Provincial Park in #CapeBreton. Here’s our answer:

#nspoli #cbpoli #NovaScotia #CapeBretonHighlands #CB #NS ImageImage
Sand and soil are eroded rock. Red sand and soil, like at #CabotsLanding, eroded from rock with significant iron content. Iron oxidizes/rusts when exposed to air, so the red is rusted iron.

#nspoli #cbpoli #NovaScotia #Capebreton #CB #NS ImageImage
The sand, soil and clay at #CabotsLanding are glacial outwash - sediments deposited by glaciers as they melted at the end of the last ice age 10,000 years ago. Much of the sediment is eroded from the #CapeBreton Highlands, which used to be much bigger.
#nspoli #cbpoli #NovaScotia Image
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We love getting questions about #mining, #minerals and #geology! We were asked about the historical #Torbrook iron mines in #AnnapolisCounty. Here’s our answer:

#nspoli #NovaScotia #NS
@GlavineLeo @KeithIrvingNS
@JohnLohrMLA @mmillershubie @scottbrison @AVRCE_NS @StephenMcNeil Image
Also in 1825, the #Annapolis Iron Mining Co. built a blast furnace at #MooseRiver (#Clementsport) to smelt the magnetic ore recovered from three seams in #Clementsvale (the Miller, Potter and Milbury), as well as to accommodate production from the #Nictaux deposits.
#nspoli #NS Image
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We love getting questions about #mining, #minerals and #geology! In response to our post yesterday about how #NovaScotia’s #gold deposits formed, we were asked about “barrel quartz.” Here’s our answer:

#nspoli #NS #CB #capebreton #Waverley @waverleyns @SteveStreatch @Bill_Horne ImageImage
Barrel quartz is a term used to describe the #gold deposit on #LaidlawHill in #Waverley in the 1800s. It isn’t a technical/geological term. The miners used it to describe what they saw: folded, gold-bearing quartz veins whose outcrops are corrugated and resemble barrels.
#nspoli Image
The quartz veins that host the #gold are hard and surrounded by soft shale. When the rocks were compressed by forces resulting from tectonic plate collision, the quartz vein buckled to form barrel shapes but the surrounding shale reacted like toothpaste and absorbed the pressure. Image
Read 11 tweets
We love getting questions about #mining, #minerals and #geology!
We were recently asked about historical #coal mining in #Thorburn, #NovaScotia. Here’s our answer:

#nspoli #NS #Pictou #PictouCounty @ns_moi @NS_Museum ImageImage
@ns_moi @NS_Museum The #Pictou coalfield is roughly 18x6 km and comprises 15 major coal seams in the #Westville, #Stellarton, and #Thorburn-Greenwood areas. Although small, the coalfield has produced about 55 million tonnes in the last two centuries.
#nspoli #NovaScotia #NS Image
@ns_moi @NS_Museum #Coal was discovered in the #Pictou coalfield around 1790 by Scottish settlers. The first substantive #mining operation was Collier John MacKay’s mine, sunk in 1809 on the west side of #EastRiver.
#nspoli #NovaScotia #NS Image
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150 victims of the #Titanic are buried in 3 #Halifax cemeteries: Fairview Lawn, Mount Olivet and Baron de Hirsch. 149 have #headstones from the Hanson #Quarry in #NB. A #Dal prof spent 15 years figuring out where the stones are from cuz there are no historical records.
#nspoli Image
The stones and the #quarry were tested for #mineralogy, texture, chemical composition and age to see if they matched. That's harder than it sounds - the original rock is no longer in the quarry (it was extracted) and these features can vary within a deposit.
#nspoli #NovaScotia Image
Still, the analysis suggests the stones, donated by #titanic-owner #WhiteStar in 1912, are almost certainly from there.
The #headstones are 422 million-year-old #gabbro (aka black #granite) and a popular #Halifax tourist attraction.
#nspoli #NovaScotia #NS #cbpoli #NewBrunswick Image
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