Pete Bowden

@peterlbowden1.bsky.social

387 Followers 158 Following

Mylonites, migmatites & metamorphism. With some pseudotachylite thrown in for light relief.

Purple marsh orchids with yellow buttercups in a lawn in the Isle of Lewis
Two people stand inside the remains of a stone building inside an Irish ring fort called Leacanabuaile.
Two people have climbed to the top of the inside wall of this ancient Irish ring fort, using the stepped construction.
A large wave is breaking with a fine white cloud of spray being blown backwards by a strong wind.
The snow covered triangular peak of Schiehallion on a bright spring day.
Bright yellow flowers amongst the grass on the headland north of Mealasta slipway, west coast of the Isle of Lewis. Look like the Bog Asphodel, (Blioch in Gaelic), in a recent post by Frank Rennie.
A grey meta gabbro shows speckled appearance towards top of the photo. The minerals become elongate and to define a curved tectonic fabric which becomes smeared out in a shear zone seen in the lower part of the photo. Seen on the west coast of the Isle of Lewis.
Brown and dun coloured outcrop of meta-ultrabasic, Maraig, Isle of Harris.
Large open fold in grey and brown Lewisian gneiss contorts the foliation. The outcrop resembles a rock formation seen in the "Monster Hunter Wilds" computer game
Small tributary stream building a delta into larger brown, (peat stained) stream. The sedimentary features observed in the yellow sand are emphasised by black heavy mineral concentrations.
Pale brown to fawn coloured polygonal shaped lichen colonies covering an outcrop of Lewisian gneiss on the Isle of Grimsay in the Outer Hebrides. The units are generally between 5mm and 15mm.
Banded black, grey and white gneiss shows minor S shaped folds in sheared Lewisian gneiss. Berneray, Outer Hebrides.
A black Outer Hebrides dyke cuts across the pre-existing foliation in grey Archaean Lewisian gneiss. Thin apophysis (offshoot) and the hinge zone of the folded dyke exhibit near perpendicular angular discordance to the foliation. These rocks were folded during Laxfordian deformation and strong flattening in the limbs of the folds brought the contact of the dyke and the foliation into concordance. This outcrop is located west of the village of Rhenigidale, Isle of Harris, Outer Hebrides.
Black Outer Hebrides Basic dykes were intruded into the paler grey Archean Lewisian gneiss prior to Laxfordian deformation. At this location the deformation produced tight recumbent folds especially in the darker rocks. Approximately 0.5km south west of the village of Rèinigeadal, (Rhenigidale), N. Harris, Outer Hebrides.
Tall grey cliffs being battered by a rough sea. Older grey Lewisian gneisses and black amphibolites are intruded by salmon-pink granitic pegmatites and aplites of Late-Laxfordian age. The cliffs are located near the Mangersta bothy on the west coast of the Isle of Lewis, Scotland.
Grey and pale green banded rocks (mylonitic gneiss) contorted by folds and sub horizontal thrusts. Traigh Shanndaigh near Ness, Isle of Lewis.
Predominantly grey rock has yellow coloured bands and porphyroclasts picking out a mylonitic fabric which has been repeatedly folded. Early isoclinal folds, with near parallel limbs, have been tightly tightly refolded. The southern end of the beach has some of the best folding I have seen, (when not obscured by sand). The beach, Traigh Shanndaigh, near Eòrapaidh (Eoropie) is located at near the top (northern end) of the Isle of Lewis and faces the Atlantic.
A deserted sweeping bay with pale sandy beach backed by high sand dunes covered in Marram grass. The sea is dark turquoise to Prussian blue in the sunlight.
A selection of books is displayed on a large slab of grey and pink Lewisian gneiss situated in the centre of Stornoway public library. The large block was sourced from a local quarry and has some cut and polished surfaces which show the tectonic foliation and some minor folds. A pink pegmatite vein in the centre of the top surface cuts across the gneissic foliation.
Banded grey Lewisian gneiss with some thicker layers of white or pink granitic pegmatite and black amphibolite show complex folding. In some cases the folds are affected by shearing. The outcrop is well exposed and clean, having been wave washed to keep it clear of surface algae/shellfish/seaweed. The compass-clinometer scale is 15cm long.
A spectacular seascape on the west coast of the Isle of Lewis with waves breaking on rocks at the base of high cliffs. The grey and pinkish grey Lewisian gneisses show complicated folding and faulting, often offsetting dark grey to black Outer Hebridean dykes, (also Lewisian in age these were formerly called Scourie dykes).
Alternating thin black, grey and pale brown bands are disrupted by a shear zone along the axial plane of a fold, (scale is approx. 15cm long). These pillow lavas are so severely flattened that it is almost impossible to identify the original pillow structures. Found in a Svecofennian greenstone belt, located on the island of Kumlinge in the Åland Islands, Finland.
A clean coastal exposure shows irregular ellipsoid pillow lavas. The pillows are grey to greenish-grey in colour, occasionally there are fawn - pale brown rims. The pillow shapes are often emphasised by the contrasting dark-grey to black interstitial material between the pillows. The outcrop is approximately 2m. wide towards the top of the photo. These basic volcanic lavas form part of a mixed sequence of supracrustal rocks in a greenstone belt of Svecofennian age. Located on the northern coast of Kumlinge, Åland Islands, Finland.
Alternating black, grey and pale brown bands are crumpled by small scale folding (scale is approx. 8cm long). These are severely flattened pillow lavas in a Svecofennian greenstone belt. located on the island of Kumlinge in the Åland Islands, Finland.
A dark grey basalt dyke is covered in pale greenish grey lichen with occasional patches of yellow lichen . The dyke cuts through green unbedded volcanic tuff containing fragments up to 25cm in diameter. The dyke exhibits an "en-echelon" arrangement where it pinches out and then continues with a slight offset. Scale is 150cm walking pole (to left of dyke). This location is very close to the coastal path below St Monans church.
Pale buff coloured sandstones of Lower Carboniferous age show repeated units of cross-bedding, (scale given by 10cm red & white compass clinometer in centre).
A group of small folds picked out by a pale layer in predominantly grey mylonitic Lewisian gneiss. The outcrop is on a beach, north-west Isle of Lewis, Scotland.