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#sediment

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DoomsdaysCW

Gateway to the #underworld: The enormous #permafrost '#megaslump' in #Siberia that keeps getting bigger

The growing "gateway to the underworld," officially known as the #BatagayMegaslump, is the largest megaslump in the world and exposes permafrost layers that are 650,000 years old.

By Sascha Pare
published September 13, 2024

"The 'gateway to the underworld' is a colossal, expanding crater in Siberia's permafrost. It is officially called the #Batagay (also spelled #Batagaika) crater or megaslump and formed when a portion of hillside in the #YanaUplands collapsed in the 1970s.

"However, the crater wasn't discovered until 1991, when satellite images revealed a rounded cliff face towering over a huge depression in the frigid landscape.

"The Batagay crater is the largest megaslump in the world, measuring 3,250 feet (990 meters) wide as of 2023. The cliff face at the top of the formation, or headwall, stands 180 feet (55 m) high.

"When it opened, the gateway exposed layers of permafrost that had been frozen for up to 650,000 years — the oldest permafrost in Siberia and the second-oldest in the world, after relict ground ice in #Canada's #YukonTerritory that is about 740,000 years old. Recently, researchers found that the gateway is expanding annually by about 35 million cubic feet (1 million cubic meters), with the depression sinking further into the ground and exposing new layers of ancient permafrost.

"The headwall of the gateway is also retreating at a rate of 40 feet (12 m) per year due to permafrost thaw, discharging massive amounts of ice and sediment into the crater, according to a 2024 study. Some of this melt material may remain in the crater, but #sediment and ice also washes into the #BatagayRiver valley at the far end of the gateway, researchers noted in the study.

"The permafrost in this region is 80% ice, which is likely why the hillside slumped in the first place, Thomas Opel, a paleoclimatologist at the Alfred Wegener Institute in Germany who has studied the gateway to the underworld, previously told Live Science.

"The gateway sits in a landscape of larch and birch #woodlands that became the target of #deforestation from the 1940s onward. Deforestation caused the #topsoil to rapidly erode and expose the underlying permafrost, which — due to its icy composition — melted more quickly than if it had been richer in sediments. Significant melting during the following decades caused the hillside to disintegrate and collapse, Opel said."

Read more:
livescience.com/planet-earth/a

Live Science · Gateway to the underworld: The enormous permafrost 'megaslump' in Siberia that keeps getting biggerBy Sascha Pare
#ClimateChange#Methane#Melting
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Or M. Bialik

New paper!
We usually think of #sediment getting finer as we move away from the shore. But, when biogenic and oceanographic factors come into play in the #mesophotic zone, the patterns could be quite different.
I'm really happy with how this paper came out. It's a very holistic view of how sedimentary #facies are actually distributed, with #seafloor photography, acoustic imaging, sampling, quantitative thin section analysis, and #multivariant statistics.
link.springer.com/article/10.1

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Or M. Bialik

One of the interesting things that happened once #animals #evolved was that they started to make holes in the #sediment. This not only opened a new niche once they figured out how to dig but also changed how some elements (e.g., sulfur) exchanged with the water above. (nature.com/articles/ngeo2537).
Already in the late Ediacaran, some things began to go into the sediment (doi.org/10.1130/G32807.1), which opened up the sediment from diffusive to advective mode of flux (doi.org/10.3389/fmars.2022.103).

NatureProtracted development of bioturbation through the early Palaeozoic Era - Nature GeoscienceMobile organisms first appeared in the fossil record prior to the Precambrian–Cambrian transition. Sediment textures indicate that the degree of sediment mixing by animal activity remained low for 120 million years following the transition.
Continued thread
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Auscandoc

But on to the more important.... “Crawford Lake, where the start of the #Anthropocene has provisionally been identified with a wafer-thin deposit of #sediment located under 22 metres of water plus several more centimetres of mud. Should the Anthropocene ultimately win recognition as a distinct unit of geologic time, its corresponding GSSP is more likely to be identified on a detailed photo of a core sample that was extracted from the lake earlier this year.”

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AnthropoceneMan

The angle of repose on a beach face is directly related to grain size and roundness, with grain size (positive correlation) seemingly more important than roundness (negative correlation). This is perhaps the steepest beach in the Northwest…and maybe with the roundest sediment.

I call this bowling ball beach, because when the waves lift and move the cobbles, it sounds like pins falling at a bowling alley…and because the stones are very obviously shaped.

Beach beneath Yaquina ahead Lighthouse showing steep beach face, nearshore sea stacks and lighthouse peering through the fog.
Closeup of beach face showing course pebble-cobble sized clasts of well rounded basalt.
Close up of pebble-cobble sediment in beach with greasy gray patina from reflected light off wet surfaces
#Oregon#beach#basalt
Public
beSpacific

The #alga #Melosiraarctica, which grows under #ArcticSea ice, contains ten times as many #microplastic particles as the surrounding #seawater. This concentration at the base of the #foodweb poses a threat to creatures that feed on the algae at the sea surface. Clumps of #deadalgae also transport the #plastic with its #pollutants particularly quickly into the #dee sea & explains high #microplastic #concentrations in the #sediment there. phys.org/news/2023-04-arctic-i

Phys.orgArctic ice algae heavily contaminated with microplastics, reports new researchBy Science X
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AnthropoceneMan

Like sand through an hourglass…

Found old set of slides of #fieldwork…and wondered the fate of The Breakers Condominiums in Neskowin, #Oregon. In 1989, there was an erosional scarp at the base of the shallow foredunes that a set of condos had just been built upon…threat was high enough that a permit to construct a rip-rap shoreline control structure was obtained.

Forward 30+ years…and the buildings still stand, protected by a substantial revetment of rock. The system has likely needed to be repaired over the decades.

Interesting, little further building has been permitted north of this point…and threat of #erosion persists in this area with scant #sand supply to the #beach…and the foredune which much of the town is built upon is backed by a tidally influenced wetland which also traps #sediment.

The entire south end of the #littoral cell has now been hardened by rip-rap. The foredunes now gone, and habitat with it.

The Breakers Condominiums in Neskowin, Oregon circa 1989. Photo shows 5 identical narrow residences atop a shallow dune with a severely eroded base.
Long view down the heavily eroded base of the foredune at Neskowin, OR in 1989…before any shoreline protection structures had been built in the area. Total height of dunes approximately 8’ tall. Moderately wide and gently sloping sandy beach.
Public notice sign of intent to build a “rip-rap revetment” at The Breakers Condominiums in Neskowin, Oregon in 1989. Believed to be the first such protection structure in the area at the time.
Aerial photo of The Breakers development (now called Neskowin Vacation Rentals by Meredith) showing the now 30+ year old tip-rap structure that was the first in the littoral cell. Note that though there is additional setback in the development to north, it has also had to be protected by rip-rap…as had every structure to the south for a kilometer.
#AnthropoScenes#PNW#SLR
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AnthropoceneMan

#Bonsai #BonsaiSoil #Trees #Soil
#Sediment #TinyTrunkThursday

Bonsai soil typically consists of pumice, scoria (vesicular lava) and imported or local clay.

1st Photo - Crushed shale screened to approximately 2mm sized grains for use as a bonsai soil. Coarser fraction (left to be used for bottom aeration layer) and center mixed with other components to form suitable soil mix.

2nd - Candidate Oregon “Mystery” clay purchased from a “friend” who won’t tell me where he gets it…for use in testing its properties.

3rd - Mixture of black basalt scoria lava, white pumice and black charcoal to be used in bonsai soil mix.

4 - Closeup of imported Japanese Akadama clay. Akadama means “red ball earth” and is the primary soil used for bonsai world round.

My goal is to find suitable soils found locally that support all horticultural needs of tiny trees in pots:

A composition with appropriate CEC, moisture retention, soil structure retention and mineral supply to support potted trees.

Shale screened to 2mm for use as bonsai soil. Bright green sieves with varying sized opening grates shown with retained shale in each interval.
Closeup of Oregon mystery clay being tested for use as Akadama substitute Brown rough exteriors with notable rootlets still present. Soil particles approximately 2-3mm
Pumice (white particles), angular charcoal (pitch-black), and scotia basalt (dark gray-black) in 2-3 mm sizes.
Akadama (imported clay from Japan) granules for use in bonsai soil is orangish brown, and rounded particles
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