#lewisian — Public Fediverse posts

A #FridayFold from the west coast of the #IsleofLewis.

The dark mafic #OuterHebrides dykes were intruded into the #Lewisian gneiss. The original cross cutting relationship has been brought into near concordance during subsequent #Laxfordian deformation which also generated these folds.

A #FridayFold from the west coast of the #IsleofLewis.

The dark mafic #OuterHebrides dykes were intruded into the #Lewisian gneiss. The original cross cutting relationship has been brought into near concordance during subsequent #Laxfordian deformation which also generated these folds.

Tiger stipe camouflage isn't really effective on the west coast of the #IsleofLewis👀
Compositional (rhythmic?) banding is preserved locally within an occurrence of #Lewisian "Older Basic Suite" meta-basics/ultrabasics.
#Archaean

Tiger stipe camouflage isn't really effective on the west coast of the #IsleofLewis👀
Compositional (rhythmic?) banding is preserved locally within an occurrence of #Lewisian "Older Basic Suite" meta-basics/ultrabasics.
#Archaean

Tiger stipe camouflage isn't really effective on the west coast of the #IsleofLewis👀
Compositional (rhythmic?) banding is preserved locally within an occurrence of #Lewisian "Older Basic Suite" meta-basics/ultrabasics.
#Archaean

#FieldtripFriday revisited. In 1975 I visited this unconformity on the north side of Loch Assynt where #Torridonian sandstones and conglomerates overlie #Lewisian gneiss.
I even spotted the ledge I climbed onto to point out the unconformity surface to my classmates.
#Geology

#FieldtripFriday revisited. In 1975 I visited this unconformity on the north side of Loch Assynt where #Torridonian sandstones and conglomerates overlie #Lewisian gneiss.
I even spotted the ledge I climbed onto to point out the unconformity surface to my classmates.
#Geology

Attenuation of the limbs in these folds has left some of the fold hinges essentially floating.
#Laxfordian folding on the north west coast of the #IsleofLewis

#TectonicTuesday #Geology #Lewisian #Folding

Attenuation of the limbs in these folds has left some of the fold hinges essentially floating.
#Laxfordian folding on the north west coast of the #IsleofLewis

#TectonicTuesday #Geology #Lewisian #Folding

#MinCup23 Here's a gorgeous big zircon crystal in a rock thin section of a Lewisian gneiss from Rodil in South Harris. Field of view about 2mm wide. 🥰 🤩 #VoteZircon #Geology #Mineralogy #Lewisian

#MinCup23 Here's a gorgeous big zircon crystal in a rock thin section of a Lewisian gneiss from Rodil in South Harris. Field of view about 2mm wide. 🥰 🤩 #VoteZircon #Geology #Mineralogy #Lewisian

#MinCup23 Here's a gorgeous big zircon crystal in a rock thin section of a Lewisian gneiss from Rodil in South Harris. Field of view about 2mm wide. 🥰 🤩 #VoteZircon #Geology #Mineralogy #Lewisian

#MinCup23 Enjoy FUN WITH ZIRCON - award-winning short video by Glasgow student Mirren Green, to accompany her final year lab project in 2019 😊 Vote zircon!!! #Zircon #Geology #Mineralogy #Iona #Lewisian https://youtu.be/W_GuozXgpR8?si=VmkehYZVqE2h_bqW

#MinCup23 Enjoy FUN WITH ZIRCON - award-winning short video by Glasgow student Mirren Green, to accompany her final year lab project in 2019 😊 Vote zircon!!! #Zircon #Geology #Mineralogy #Iona #Lewisian https://youtu.be/W_GuozXgpR8?si=VmkehYZVqE2h_bqW

#MinCup23 Enjoy FUN WITH ZIRCON - award-winning short video by Glasgow student Mirren Green, to accompany her final year lab project in 2019 😊 Vote zircon!!! #Zircon #Geology #Mineralogy #Iona #Lewisian https://youtu.be/W_GuozXgpR8?si=VmkehYZVqE2h_bqW

#MinCup23 Dioptase vs zircon: dioptase is THE GREEEN, but not a lot else. Zircon does all the colours, twinkles/sparkles, is the BEST STORYTELLER, and glows gold under UV light. Also, it's never won the mineral cup, and really deserves to. This concentration of megazircons (up to 5mm or so) under 254nm UV light, is from a Lewisian ultramafic gneiss in Iona. #Geology #Zircon #Lewisian

#MinCup23 Dioptase vs zircon: dioptase is THE GREEEN, but not a lot else. Zircon does all the colours, twinkles/sparkles, is the BEST STORYTELLER, and glows gold under UV light. Also, it's never won the mineral cup, and really deserves to. This concentration of megazircons (up to 5mm or so) under 254nm UV light, is from a Lewisian ultramafic gneiss in Iona. #Geology #Zircon #Lewisian

... and also from yesterday, here's a wee handful of proper Iona greenstones: pebbles of Lewisian serpentine marble. There is a lovely range of textures and colours in these marbles. I never get tired of them 🥰 🤩 😊 #Geology #Iona #Lewisian #Pebbles

... and also from yesterday, here's a wee handful of proper Iona greenstones: pebbles of Lewisian serpentine marble. There is a lovely range of textures and colours in these marbles. I never get tired of them 🥰 🤩 😊 #Geology #Iona #Lewisian #Pebbles

... and also from yesterday, here's a wee handful of proper Iona greenstones: pebbles of Lewisian serpentine marble. There is a lovely range of textures and colours in these marbles. I never get tired of them 🥰 🤩 😊 #Geology #Iona #Lewisian #Pebbles

#FridayFold - #Lewisian gneiss on approach to the causeway from South Uist to Eriskay in the #OuterHebrides

#FridayFold - #Lewisian gneiss on approach to the causeway from South Uist to Eriskay in the #OuterHebrides

Has anybody seen this rock type in the #Lewisian of NW Scotland?

These examples are in the Ness Assemblage on the west coast of the #isleoflewis

Has anybody seen this rock type in the #Lewisian of NW Scotland?

These examples are in the Ness Assemblage on the west coast of the #isleoflewis

Ultrabasic boudins and 'pods' frequently occur in #Lewisian gneisses on the #IsleofLewis.
These examples are on the beach at Port Nis (Port of Ness), near the northern end of the island.

Ultrabasic boudins and 'pods' frequently occur in #Lewisian gneisses on the #IsleofLewis.
These examples are on the beach at Port Nis (Port of Ness), near the northern end of the island.

Another hard day in the office😎 looking for a #FridayFold

The #Lewisian gneisses on the beach at Port Nis (Port of Ness) have been folded during the #Laxfordian.
#IsleofLewis

Another hard day in the office😎 looking for a #FridayFold

The #Lewisian gneisses on the beach at Port Nis (Port of Ness) have been folded during the #Laxfordian.
#IsleofLewis

#Torridonian on Tuesday.

Glacial erratic on the north-west coast of the #IsleofLewis.
After a couple of hours trying to figure out what was going on in the grey #Lewisian mylonites🤓 I was ready for a distraction.

#Torridonian on Tuesday.

Glacial erratic on the north-west coast of the #IsleofLewis.
After a couple of hours trying to figure out what was going on in the grey #Lewisian mylonites🤓 I was ready for a distraction.

Large granitic pegmatites cut across the South Harris Meta-igneous Complex and show complex intergrowth patterns picked out by black biotite.

We returned via Bagh Steinigidh where a narrow slice of #Lewisian meta-sediments contain folded marble bands.

Large granitic pegmatites cut across the South Harris Meta-igneous Complex and show complex intergrowth patterns picked out by black biotite.

We returned via Bagh Steinigidh where a narrow slice of #Lewisian meta-sediments contain folded marble bands.

Fun couple of days exploring the local #Lewisian geology with
@early_earth_tim

Firstly the #Archean (approx. 2.8 billion years old) ultrabasic intrusions at Maaruig (Maraig).

Then 3D outcrop mapping #Laxfordian folds in the Ness assemblage supracrustals at Eoropaidh (Eoropie).

Fun couple of days exploring the local #Lewisian geology with
@early_earth_tim

Firstly the #Archean (approx. 2.8 billion years old) ultrabasic intrusions at Maaruig (Maraig).

Then 3D outcrop mapping #Laxfordian folds in the Ness assemblage supracrustals at Eoropaidh (Eoropie).

These #Lewisian #Migmatites escaped Laxfordian reworking relatively unscathed.
Ardivachar, South Uist in the Outer Hebrides

These #Lewisian #Migmatites escaped Laxfordian reworking relatively unscathed.
Ardivachar, South Uist in the Outer Hebrides

Something for the #garnet fans.

#Lewisian garnet-amphibolites on the shoreline west of Balivanich, N. Uist in the Outer Hebrides

Something for the #garnet fans.

#Lewisian garnet-amphibolites on the shoreline west of Balivanich, N. Uist in the Outer Hebrides

Not quite #Tarmageddon, but another example of an unpleasant #anthropocene unconformity😠.

Recent #Targlomerate overlying #Lewisian reworked migmatites; so an age gap of getting on for 2 billion years🤪

Luckily this was an exception on an otherwise pristine #Hebridean coastline

Not quite #Tarmageddon, but another example of an unpleasant #anthropocene unconformity😠.

Recent #Targlomerate overlying #Lewisian reworked migmatites; so an age gap of getting on for 2 billion years🤪

Luckily this was an exception on an otherwise pristine #Hebridean coastline

#ThinSectionThursday Here's a wonderful rock (garnet-scapolite pyroxenite, with feathery symplectite intergrowths around the garnets) from the Lewisian metamorphic complex in South Harris, in both plane polarized light, and between crosed polars. The field of view is about 2mm. See ALT text for detailed image descriptions. #Lewisian #Metamorphic #Rocks #Minerals.

#ThinSectionThursday Here's a wonderful rock (garnet-scapolite pyroxenite, with feathery symplectite intergrowths around the garnets) from the Lewisian metamorphic complex in South Harris, in both plane polarized light, and between crosed polars. The field of view is about 2mm. See ALT text for detailed image descriptions. #Lewisian #Metamorphic #Rocks #Minerals.

#ThinSectionThursday Here's a wonderful rock (garnet-scapolite pyroxenite, with feathery symplectite intergrowths around the garnets) from the Lewisian metamorphic complex in South Harris, in both plane polarized light, and between crosed polars. The field of view is about 2mm. See ALT text for detailed image descriptions. #Lewisian #Metamorphic #Rocks #Minerals.

More mafic banded gneiss , in contact with paler granitic gneisses, cut by a little late fracture. #Lewisian #Iona

A wee thread of lovely #Lewisian gneisses from the west coast of #Iona this morning. Dextral shear indicated by S-shaped felsic segregation in dark amphibolitic layer.