SXR339

GLEN GAIRN: NJ 294 008

Locality 1 Low-angled slabs beside road
•    Pale medium grained granite
•    Joints
Locality 2 Flat exposures near tree line
•    Pinker granite (more alkali feldspar)
•    Blob like pegmatite – feldspar crystals up to 6cm (gas rich magma has fewer nucleation sites leading to larger crystals)
Locality 4 Exposures near birch and pine trees
•    Metamorphosed dalradian sediments with foliation (schist). Folded.
•    Sharp contact with granite
•    No chilled margins or baked edges – intruded at depth (not a big temperature difference)
•    Evidence of other magmatic rock types (diorite, feldsite)
Locality 3 Crags west of Little Craig
•    Coarser grained, biotite poor granite
•    Sharp contact with sediments
•    Huge pegmatite block

WOLVES ROCK – Above Kindrogan field centre
•    Large fallen block of Pitlochry schist with garnets (2 - 4 mm) [garnet mica schist]
•    Well defined depositional layers. Strong foliation – larger, redder garnets, weaker foliation – smaller oranger garnets (less Fe)
•    Foliation around garnets (pre or syn kinematic)



NIGG BAY: NJ 965 049

Going away from carpark
Locality 1
•    50:50 mix of granite and schist
•    Migmatite
•    Granite oozing out of foliation in schist
•    Horizontal foliation in schist
•    Granite produced by crustal melting (20-30% to release granite)
Locality 2
•    Medium grained granite (pink)
•    Less granite than before
•    Foliations more random
Locality 3
•    90:10 granite:schist
•    Granite with small blocks of country rock in random orientation
•    Fine to medium grained granite
Locality 4
•    Amphibolite
•    Sharp contact with granite
•    Boudinaged quartz

DUNKELD

•    Fold with axial cleavage
•    Beds visible
•    Antiform
•    Younging direction towards centre so downwards facing and at least 2 stages of deformation
•    Other synforms and antiforms visible

STONEHAVEN: Perthumie Bay NO 884 877; Garron Point NO 894 877.

Garron point
•    Pillow lava
•    Highland boundary fault
Skatie shore
•    Rocks show bedding (steeper 80°) and cleavage (60°)
•    Metapsamite
•    Fine to medium grained sand
•    Fining upwards
•    Some flute marks
•    Beds right way up

STRATH FIONAN: NN 717 575

Day 1
Locality 1
•    Quartzite
•    Elongated quartz grains
•    Long tabular feldspar crystals
•    Linear fabric
•    Bedding (cross stratification)
Locality 9
•    Schist
•    Garnet
•    Stautolite
•    Kyanite (did not see)
•    Crenulation lineation
Locality 6
•    Large (10mm) garnets in sheet associated with quartz
•    Garnet mica schist
•    Garnet pre or syn kinematic
•    No convincing boudinaged garnet
•    V. good crenulation

Locality 4
•    Kyanite??
Locality 3
•    Amphibolite
•    White plagioclase crystals
•    Hornblend

Day 2
Locality 11
•    Schist
•    Garnet – pre or syn kinematic (eye structures)
•    Kyanite (convincing) random orientation (cutting fabric)
•    Amphibolite with long tabular plagioclase
•    Sharp contact with schist
•    Weathering proud
Locality 10
•    Metamorphosed limestone
•    Isoclinal folds
•    Folds follow bedding
•    S- and Z- folds
•    Small outcrop of schist between limestone and dyke
•    Sharp contact between amphibolite dyke and schist
•    Garnets in amphibolite

Conclusion
•    Planar fabric – schist only
•    Linear fabric – schist (crenulation), quartzite (quartz and feldspar) and amphibolite (feldspar)
•    No fabric – limestone
•    All locations in kyanite zone but chemistry not always suitable to produce metamorphic minerals (eg kyanite needs Al)

SXR260 - The Geological History of the British Isles

Didn't we have a lovely time, the week we went to Durham?

Day 0 - Arrival and maps

This year the SXR260 Summer School was based at Trevelyan College in Durham because St Mary's which was a women only college was letting men in (or going bisexual as Colin put it). After arrival and registration, we had for an introductory lecture and then off to meet our tutor groups. I was in group 4 with Colin as our tutor. (Colin was also the coach leader and his fine entertainment was yet another highlight of the week!) We were working in pairs within our groups, but as the last person in our group did not turn up I worked with Rob and Roger who kindly let me join them. We looked at the Lake District sheet and then at the larger scale Brough sheet. We were looking at the faults we would see later in the week, and discussing the Alston and Askrigg blocks that would be another large feature of the week. We also had a demonstration of how to use a compass clinometer and tried it out on a piece of sloping board in the lab.

Day 1 - How did you get that map?

Nice channelling

Our first stop on day 1 was in the town of Barnard Castle. We were looking at an outcrop under the castle. This was our first go of the week at looking at rocks and sketching what we saw. We quickly established that it was a sandstone with evidence of water transport (no frosting, sub angular grains). There was cross bedding and channelling present. We also saw Raby castle and had our first mention of Lord Barnard. He would become a constant feature of our week's entertainment with Colin.

We continued onto our main aim of the day, mapping at Hillbeck quarry after a welcome stop at Brough (where we got a preview od some red sandstone we would see later in the week). In our group, the first stop was at location N which was our first chance to use the compass clinometer (clino) in a real setting. Examination of the lithology told us this was a dark coloured limestone (in fact the Robinson limestone). Continuing to location E we noted that the ground between us and the outcrop in front had different vegetation - tough grasses typical of a more boggy environment. We concluded that these must be growing on a different rocktype, which was confirmed by the small outcrop of mudstone visible on our traverse to location F. At location F we again took the strike and dip and looked at the lithology (Melmerby Scar limestone). We hypothesized that we were on an anticline and made predictions about the strike and dip on the other side. At location G by the horseshoe scar we confirmed our hypothesis. We saw later that this is in fact an eastward dipping anticline.

Eastward dipping anticline	Measuring strike and dip
Brachiopod

At location H we took another strike / dip reading, lithology (Robinson limestone) and looked at the outcrop high above us. We were informed that this limestone is in fact the Melmerby Scar limestone which underlies the Robinson limestone on which we were sitting. There was a fault with a large throw in front of us, the Barnum fault which is part of the Pennine fault system. We climbed up the other side to location K to see galena and baryte which were once mined here. Finally, we went to location A to see fossils of brachiopods (including Gigantoproductus giganteus) and corals and speculate on the depositional environment of the limestone being quarried (Robinson). Back in the lab we completed our geological maps and drew a cross section through the area. On the coach on the way home we were treated to the tail of Eric Bloodaxe and his horse, floggin. At the time this all seemed quite plausable until we passed the alleged grave of Eric (here lies the body of Eric Bloodaxe with floggin his dead horse...)
Five of us including Colin formed the team 'Gneissly Schist' for the pub quiz. Thanks to Colin we came second (but were leading for quite a while) and won some quite stunning quartz. Still, it could have been a plastic fossil...

View showing flat topped Wildboar fell on left (Askrigg block) and rounded Howgill fells on right (lake district block).

View showing flat topped Wildboar fell on left (Askrigg block) and rounded Howgill fells on right (lake district block)

Day 2 - Whin Sill and Waterfalls
Day 2 was a day of two halves, igneous and sedimentary. Our first stop (apart from to look at the view) was at low force. Apart from the stunning waterfalls (formed of course by the water going over a more resistant rock type), we were looking at the structure of the Whin Sill. We started by looking at the polygonal forms of the columns formed when the magma cooled. Next we looked for the chilled margin at the top of the sill, which was rather elusive. After our photo stop by the sheep, we went to the second locality which was an outcrop of sill on top of bedded country rock. This was not the bottom of the sill but either a raft or pendant of country rock within the sill. The chilled margin here was much more evident. We looked at the lithology of the Whin Sill in the Whin Sill quarry. The main Whin Sill rock is dolerite (Bagshaw's Law: if you can see the grains, it's not fine grained!), but we also saw a pegmatite band formed from the last magma to cool - by this stage it is more hydrous allowing the more mobile molecules to form much larger crystals. We continued on the coach to High Force where we saw the actual bottom of the sill (in fact Colin is holding it up!) and the structure at the waterfall where, despite appearances, the sill sits on top of mudstone with limestone underneath. There were nice fossil corals in the limestone. After lunch (and a half of Cauldron’s Snout) it was time to look at sedimentary rocks at Bowlees. We worked our way up the river noting the rock types, faults etc. This is one of the Yoredale cyclotherms. Throughout the day we had various tales of Lord and Lady Barnard, including why most of the houses in these parts are painted white (I know you will be dying to know so I better tell you that these are the one's that Lord Barnard owns).

Group 4 and Colin	View
Low force	Fossil coral (slippery when wet!)
Whin sill on top of bedded country rock	Whin Sill quarry
Colin holds up the Whin Sill	High force

In the lab we looked at thin sections of the main Whin Sill rock and the pegmatite, confirming the presence of pyroxene and feldspar in both.
Day 3 - Road, Quarry, Quarry, Quarry
Day 3 was the earliest start and latest finish of all our trips. Our first stop was the side of the A6 (overlooking the M6) at Tebay. We were here to study the structures in the Silurian rocks. We sketched the synclines, anticlines and faults (including a reverse fault), looked at the turbidites, saw fold slickensides and drags, tension cracks and flute casts. The peace and quiet at Shap Wells was welcome after all the noise. Here we saw steeply dipping Silurian rocks (with imaginary graptolytes) overlaid by early Carboniferous breccia containing pink orthoclase feldspar and clasts of weathered Shap granite (the Shap Wells unconformity). Lunch was eaten in the sunshine looking at this fabulous view. The granite plaques on the side of the Shap Wells hotel gave us a preview of what we would see later - and a plaque commemorating 25 years of OU visits. The red (or pink) Shap quarry did not disappoint. The large pink orthoclase phenocrysts were fantastic to behold, the simple twinning glinting in the sun. We studied the black enclaves of magma of a different composition that had been intruded into the main magma - orthoclase crystals from within the main magma have occasionally drifted into the enclave. The path up to the quarry was littered with rocks from the blue quarry - andesite with epidote, garnet, chalcopyrite and calcite making it a feast for the eyes. Off to our next quarry, Bongate Scar. This was a quarry for the local Brokram stone which is a very poorly sorted breccia or conglomerate (or even breccioconglomerate). There were thick fining up beds and channels as well as evidence of imbrication. This was an area of flash flooding at the edge of a desert (like areas of Death Valley today). Our final quarry of the day (Hoff) was medium grained, well sorted, well rounded frosted quartz with occasional feldspar leading to our conclusion of an aeolian origin. It showed massive cross bedding indicating dunes (in fact barchan dunes). Today's story was all about Little Musgrave and his 'partnering' with Lady Barnard...

Enclave