Last day of fieldwork in England: A working quarry and another great unconformity

June 26th, 2015

1 Doulting quarry sawBRISTOL, ENGLAND (June 26, 2015) — Tim Palmer has a professional interest in building stones, and a passion for sorting out their characteristics and historical uses. He thus has many contacts in the stone industry, from architects to quarry managers. This morning we visited the Doulting Stone Quarry on the outskirts of Doulting near Shepton Mallet in Somerset. Here a distinctive facies of the Jurassic Inferior Oolite is excavated for a variety of purposes. The rock has a lovely color, is relatively easy to work, and is durable. Above is a quarry saw that cuts out huge blocks from the natural exposure.

2 Thalassinoides layer DoultingSuch sawing produces great cross-sections for geologists to examine. We were particularly interested in that light-colored unit above with the irregular top and dark sediment-filled holes. The holes are part of a network of Thalassinoides burrows (tunnels made by Jurassic crustaceans) and reduce the value of the rock as a building stone. There is thus lots of it laying around the quarry yard for study.

3 Pinnid likely Trichites cross section DoultingOne impressive fossil exposed by the sawing is this pinnid bivalve, probably Trichites.

4 Burrow fill sediments DoultingThe Thalassinoides burrows are filled with a poorly-cemented sediment. It is full of little fossils, so we collected a bag of it for microscopic examination. It may give us clues as to what communities lived on the surface of this burrowed unit when it was part of the Jurassic seafloor.

5 shaping saw DoultingWe had a tour of the quarry shops, which included seeing these giant rock saws in action. Many of the saws are controlled by computers, so elaborate cuts can be made.

6 Medieval stone breaking marksThis rock has been quarried since Roman times, so there is over 2000 years of stone working here. The quarry owner set aside this rock face which shows chisel marks made in Medieval times. Wooden wedges were jammed into chiseled channels and then pulled over days to eventually crack the stone free.

7 Tedbury Camp wavecut surface along strikeAfter the quarry visit, Tim Palmer and I tromped through the woods and eventually found (with the help of several locals) an exposure known as Tedbury Camp. It is another Jurassic-on-Carboniferous unconformity like we saw at Ogmore-By-Sea earlier in the week. A century ago quarry workers cleared off this surface of Carboniferous limestone. It is a wave-cut platform on which Jurassic sediments (the Inferior Oolite) were deposited. The surface has many geological delights, including faults, drag folds, differentially-weathered cherts and carbonates, and Jurassic borings and encrusters. Beautiful.

8 wavecut surface foldingIn this view of the surface you may be able to see the odd folding of the dark chert layers in the right middle of the image. These seem to be drag folds along a fault. They clearly predate the Jurassic erosion of the limestone surface. The overlying Jurassic can be seen in the small outcrop on the left near Tim.

9 section view of wavecut surfaceIn this cross-section of the erosional surface you can clearly see we’re working with an angular unconformity.

10 filled borings wavecutTrypanites borings are abundant across this surface, most filled with lighter Jurassic sediment. There are other borings here too that deviate from the straight, cylindrical nature of Trypanites.

11 curved borings wavecutI don’t know yet how to classify these curved borings. They resemble Palaeosabella.

12 Encrusting bivalve wavecutHere is a Jurassic bivalve attached to the Carboniferous limestone at the unconformity. Most of the encrusters have been eroded away.

13 Tim on wavecut platformThere are many possibilities for further study of the Tedbury Camp unconformity. This was a productive site for our last field visit in England this year. Thank you very much to Tim Palmer, seated above, for his expertise, great companionship, and generosity with his time. It was a reminder of how much fun we had together in the field twenty years ago.

My month of geology in the United Kingdom has now come to an end. My next two days will be devoted to packing up and making the long train and then plane flights home. What a wonderful time I had, as did my students on the earlier part of the trip, Mae Kemsley and Meredith Mann. Thank you again to Paul Taylor for his work with us in Scarborough. I am very fortunate with my fine British friends.

For the record, the important locality coordinates from this trip —

GPS 089: Millepore Bed blocks N54.33877°, W00.42339°

GPS 090: Spindle Thorn Member, Hundale Point N54.16167°, W00.23326°

GPS 091: Robin Hood’s Bay N54.41782°, W00.52501°

GPS 092: Northern limit of Speeton Clay N54.16654°, W00.24567°

GPS 093: Northern limit of Red Chalk N54.15887°, W00.22261°

GPS 094: South section Filey Brigg N54.21674°, W00.26922°

GPS 095: North section Filey Brigg N54.21823°, W00.26904°

GPS 096: Filey Brigg N54.21560°, W00.25842°

GPS 097: D6 of Speeton Clay N54.16635°, W00.24520°

GPS 098: C Beds of Speeton Clay N54.16518°, W00.24226°

GPS 099: Lower B Beds of Speeton Clay N54.16167°, W0023326°

GPS 100: Possible A Beds of Speeton Clay N54.16129°, W00.23207°

GPS 101: A/B Beds of Speeton Clay N54.16035°, W00.22910°

GPS 102: C7E layer of Speeton Clay N54.16447°, W00.24043°

GPS 103: Lavernock Point N51.40589°, W03.16947°

GPS 104: Triassic deposits, Ogmore-By-Sea N51.46543°, W03.64094°

GPS 105: Sutton Stone Unconformity N51.45480°, W03.62609°

GPS 106: Sample of lowermost Sutton Stone N51.45455°, W03.62545°

GPS 107: Nash Point N51.40311°, W03.56212°

GPS 108; Devil’s Chimney N51.86402°, W02.07905°

GPS 109: Fiddler’s Elbow N51.82584°, W02.16541°

GPS 110: Doulting Stone Quarry N51.18993°, W02.50245°

GPS 111: Tedbury Camp unconformity N51.23912°, W02.36515°

 

Wooster Geologist in England (again)

June 25th, 2015

1 old quarry face cotswoldsBRISTOL, ENGLAND (June 25, 2015) — Our little geological exploration of southern Britain now passes into England. Tim Palmer and I crossed the River Severn and drove to the Cotswolds to examine old quarry exposures and Medieval stonework. We are parked above in Salterley Quarry near Leckhampton Hill.

2 devils chimney leckhamptonOur theme again is Jurassic. At Leckhampton Hill we examined exposures of the Middle Jurassic Inferior Oolite. It is not, of course, inferior to anything in the modern sense. The name, originally from William Smith himself, refers to its position below the Great Oolite. This is Devil’s Chimney, a remnant of stone left from quarrying in the 19th Century.

3 fiddlers elbow hdgd and Pea GritWe stopped along a bend in a Cotswold road called Fiddler’s Elbow and found an old carbonate hardground friend in the Inferior Oolite. Borings are evident in this flat, eroded surface. Next to the hammer are pieces of the Pea Grit, a coarser facies. I want to examine the grains for microborings and encrusters.

4 Dogrose leckhamptonThis is the gorgeous dog-rose (Rosa canina, not surprisingly), which is common in the Cotswolds. It is the model for the Tudor Rose in heraldry.

5 Fiddlers elbow orchidsThese tall orchids were also abundant near our outcrops.

6 fiddlers elbow orchids closeA closer view of the orchids. When I learn the name for this plant, I’ll amend this post. [And we have one! Caroline Palmer identified the flowers as Dactylorhiza sp. Thanks, Caroline!]

7 Painswick church and yewsAt the end of the day we stopped by St. Mary’s Church in Painswick, with its distinctive churchyard and variety of building stones. The sculptured trees are English yews.

8 Tim and Painswick gravestonesThe gravestones date back to the early 18th Century, with older ledger stones inside the church.

9 Painswick church pyramid markerThe unique pyramidal tomb of the stonemason John Bryan (1716-1787). He was apparently responsible for most of the 18th Century ornate monuments in this churchyard.

10 copper markers killing lichen PainswickMany of the gravestones have copper plates affixed to their upper faces. The rain washes copper ions out of the metal and over the limestone, killing the lichens and other encrusting organisms. This leaves the lighter patch of bare limestone. Somewhere in this is a study of microbiome ecological gradients!

11 St Marys church Painswick shot divot 1643The Painswick church was the site of a 1643 battle during the English Civil War. There are numerous bullet and shot marks on the exterior stones. Tim commented on the remarkable resilience of this stone to stay coherent after almost 400 years of weathering of these pits.

National Museum Wales and its new dinosaur

June 25th, 2015

1 National Museum WalesBRIDGEND, WALES (June 25, 2015) — On our last day in Wales, Tim had an errand at the National Museum Wales in Cardiff. We took the opportunity to visit their new dinosaur exhibit with the skeleton that had been collected from an outcrop we visited earlier in the week at Lavernock Point.

2 Dino displayThe exhibit is well done. The fossil skeleton represents the first carnivorous dinosaur found in Wales, and one of the earliest Jurassic dinosaurs found anywhere.

3 Lavernock dino bonesHere are some of the bones in lower Lias limestone.

4 Dino site museum imageThis is a museum photo of the dinosaur collecting site. You may recognize the place from a previous post in this blog.

Cardiff city hallThis is Cardiff City Hall. I loved the early 20th Century architecture in this Cardiff district, but we didn’t have time to explore. It is now off to southern England for more fieldwork.

A great unconformity in South Wales

June 24th, 2015

1 Dinantian Sutton unconformity wide viewBRIDGEND, WALES (June 24, 2015) — Today Tim Palmer and I visited a famous unconformable rock plane in South Wales. I last saw it thirty years ago, when I knew a lot less about eroded, bored and encrusted surfaces. It is an unconformity between a Carboniferous limestone (High Tor Limestone, Dinantian in age) and an overlying Jurassic limestone (Sutton Stone, Hettangian, Lower Jurassic) exposed on the coast near Ogmore-By-Sea. It was most thoroughly described in 2004 by Johnson and McKerrow (Palaeontology 38: 529-541). You can see it as the surface above, with the Jurassic rocks on top of it to the right. (I know, gray rocks on gray rocks. It takes close examination to tell them apart after they both have been subjected to coastal weathering.)

2 Dinantian Sutton close viewHere is a closer view with part of the Lower Jurassic Sutton Stone broken away to show fresh material. (We didn’t do this, despite the guilty-looking hammer. The hammer is Paul Taylor’s, by the way. Thanks, Paul!) Note the pebbles in the Sutton Stone. They are made of the Carboniferous limestone beneath. Classic unconformity.

3 Dinantian Sutton borings wide viewThe Carboniferous limestone is punctured by numerous small borings (Trypanites) drilled by filter-feeding worms of some kind when the Early Jurassic sea covered this surface. They are the clusters of small black dots shown above.

4 Dinantian Sutton borings closeIn this closer view of the borings you can see that they are filled with a lighter Jurassic sediment. The openings have been somewhat enlarged by weathering.

5 Dinantian Sutton reliefThis erosion surface shows some relief, probably formed by cobbles and pebbles washing over it during the Early Jurassic. This matches what we see on modern wave-cut rocky platforms.

6 Triassic Dinantian unconformityOn the same stretch of shoreline there is a small section where Triassic wadi deposits cut down into the Carboniferous limestone — another even more dramatic unconformity, but without marine fossils.

7 Triassic wadi deposits Ogmore by seaComing from a desert myself, I have an affinity for wadi sediments. They are coarse, angular and poorly sorted. These grains are entirely from the underlying Carboniferous limestone. They were likely generated from steep rocky canyons through which intermittent streams flowed.

8 Nash Point viewAt the end of the day Tim and I visited Nash Point, again on the coast of South Wales. Here the Lias is brilliantly (and dangerously!) exposed as a series of alternating limestones and shales.

9 Nash Point CliffWe didn’t get too close to these unstable cliffs. The limestone blocks fall often as the interbedded soft shales holding them in place weather away.

10 Nash PointA view of Nash Point at low tide. Tim always wears that red jacket, so he’s easy to spot. (Classic Redcoat!)

11 Nash Point cobblesWe didn’t find much to paleontologically interest us at this last outcrop, but it was beautiful on another stunning coastal day. These cobbles, all made of Lias limestones, are pretty to look at, but tiresome to walk through. We were ready for a slow dinner after this excellent day.

 

Wooster Geologist in Wales

June 23rd, 2015

1 Triassic Lavernock Point Penarth GroupBRIDGEND, WALES (June 23, 2015) — My train journey yesterday was successful. It was close, but I made the four tight connections and arrived in Aberystwyth, Wales, from Thurso, Scotland, on schedule. It took 15 hours. My friend Tim Palmer was there to greet me as I stumbled out of my carriage. I went from rainy, cold Scotland to warm and sunny Wales. The top image is of the Triassic/Jurassic transition at Lavernock Point in south Wales (see below).

2 Tim Caroline houseMy first Welsh night was with Tim in his great country home (with is wife Caroline) on the outskirts of Aberystwyth. It is called The Old Laundry because of its function on a previous manorial estate. I had my best sleep here for the entire trip. Quiet and beautiful.

4 Talley Abbey ruinsOne of Tim’s passions is the study of building stones in England and Wales. As we drove to southern Wales for our geological work, we stopped by interesting stone structures, including the ruins of Talley Abbey, a 12th Century monastery.

5 Tim at Talley AbbeyTim is here examining the dressing stones on a corner of this pillar in the Talley Abbey ruins. I learned that these dressings are usually made of stone that can be easily shaped, is attractive, and will hold sharp edges. In many cases these are called “freestones”.

6 Lower Lias Lavernock dinosaur siteOur first geological stop was at Lavernock Point on the southern coast of Wales. We looked here at the boundary section between the Upper Triassic and Lower Jurassic (Lias). In this view we see an alternating sequence of limestones (buff-colored) and shales (dark gray) of the lower Lias. These are marginal marine units with oysters and ammonites. On the left side of the image you can see a broad niche cut back into the cliff. This is the site where the first carnivorous dinosaur in Wales was recently excavated. It is also one of the oldest Jurassic dinosaurs since it was discovered just above the Triassic/Jurassic boundary. More on this dinosaur later.

7 Lower Lias pseudo mudcracksWe wandered across broad intertidal wave-cut platforms at Lavernock Point looking at the limestones and shales of the lower Lias. I was intrigued by these features on some bedding planes. They are not desiccation cracks, but rather some combination of jointing and weathering.

8 Liostrea hisingeri LavernockThe oyster Liostrea hisingeri is very common in this part of the Lias. In the limestones it is sectioned by erosion, resulting in these shelly outlines.

9 Liostrea hisingeri shale LavernockWhen Liostrea hisingeri is present in the shales, it is preserved three dimensionally.

10 Tonypandy street viewAfter our geologizing was done for the day, Tim and I drove up into the Rhondda Valleys just north of our hotel. This was at one time a very busy coal mining and industrial region, but the mines are closed and most of the heavy industry has moved elsewhere. Above is a view down a street in Tonypandy, one of the more famous towns of The Valleys. There were massive riots here in 1910 which eventually a minimum wage for miners in 1912.

Another long train journey through Great Britain

June 22nd, 2015

1 Thurso stationTHURSO, SCOTLAND (June 22, 2015) — Back to the trains today as I leave for a long journey south through Scotland and central England and then west to Aberystwyth, Wales, to spend some quality field time with my friend Tim Palmer. Our goal will be to explore sites for potential Independent Study projects.

4 Screen Shot 2015-06-24 at 8.51.34 PMLots of time on the trains coming up on this trek. Even more if I miss a connection. British train journeys often include only a few minutes to change trains at a station. This is not always a straightforward task.

2 Thurso track endsThe tracks at Thurso are the most northerly extension of the British rail system.

3 Tracks from ThursoSouth I go. There is no other direction!

A Day in Stromness

June 21st, 2015

1 Stromness Museum sceneSTROMNESS, SCOTLAND (June 21, 2015) — I intended to explore the region around Stromness today as I waited for the late afternoon ferry to Thurso, but it rained continuously. Since I can’t afford to get my meager kit wet while traveling, I was confined to indoors activities, including visiting the excellent though small Stromness Museum.

2 Labradorite as ballastThe bulk of the museum displays are devoted to maritime history, naturally, but there is always some geology. This, for example, is a beautiful piece of labradorite (from, naturally, Labrador) used as ship ballast.

3 Hugh Miller fossilI was very pleased to see this small exhibit on the brilliant polymath Hugh Miller (1802-1856) and the fossils he collected from Devonian rocks in the region. This is his most famous specimen: “The Asterolepis of Stromness”. He was the earliest expert on the Old Red Sandstone and its fossils.

This afternoon I take the ferry across these stormy seas back to the Scottish mainland. I’ve very much enjoyed Orkney, cold and wet though it is.

Neolithic Orkney

June 20th, 2015

1 Brodgar Ring Stone and MoundSTROMNESS, SCOTLAND (June 20, 2015) — After our last sessions of talks in the 2015 Larwood Symposium, we had a guided tour of some spectacular Neolithic sites on the island of Mainland in Orkney. (I know, an island called Mainland. That’s why I linked it.) Above is a standing stone from the Ring of Brodgar, a stone circle just a few miles from Stromness. It is part of a World Heritage Site and is very dramatic (especially with a stiff wind off the North Atlantic).

2 Ring of Brodgar weatheringHere is a side view of the stones, with Paul Taylor for scale. They are made of the ubiquitous Old Red Sandstone. Note that when you stand such stones with their bedding vertical like this, the rain works its way between the layers, causing it to split and exfoliate over time. Of course, considering that these stones were erected between 2500 BCE and 2000 BCE, they’re in pretty good shape!

3 Climbing ripples Brodgar stone rotatedA geology moment: This is a side view of one of the Old Red Sandstones, which I’ve rotated horizontal (the image, not the stone!). You can see beautiful climbing ripple laminae.

4 Stenness StonesThe Standing Stones of Stenness may be the oldest such Neolithic structure in Britain. For me it was the most evocative of this ancient and mysterious activity, even if it is the most manicured ring.

5 Stenness StoneThis Stenness stone is one of the most photographed rocks in Orkney.

6 Maes Howe from roadMaes Howe is a Neolithic chambered cairn, possibly built about 2800 BCE. We see here a simple mound across a flat field. The interior is a complex main room with side passages and interior standing stones. This was likely a grave site, but no bones have been discovered in it.

7 Maes Howe closerI wish I could show you the interior, but photography was not allowed. Our party, along with many others, crowded into the chamber after passing through the long and narrow entrance tunnel. Our guide was particularly good at telling the stories of the site and pointing out various archaeological features. On many of the stones are delightful examples of much later Viking runic inscriptions (ancient vandalism, really!).

8 Stabilized beach dunesThe Orkney coastlines have many partially stabilized beach dunes, like these grass-covered examples. Storms, though, can quickly erode them and move vast quantities of sand. Such events have uncovered buried archaeological sites on the shorelines, such as Skara Brae below.

9 Skara BraeSkara Brae is a Neolithic village that was buried for many centuries under such sand dunes. It is now one of the best known archaeological sites in Britain. The sand and sod has been removed from the top of a network of homes and pathways, giving the immediate appearance of World War I trenches.

10 Skara Brae houseThis is one of the homes. It is preserved in remarkably good shape, with all the stone furnishings still in place.

11 Skara Brae mystery stoneThere are many mysterious objects associated with the Skara Brae site, including this fist-sized elaborately carved stone. Any ideas as to its function? Paul Taylor thinks stones like this may have been used for hunting, tied together as bolas.

12 Laird of Skaill captured Bolshevik bannerJust because I find it interesting, here is a banner displayed in the local Laird of Skaill home near Skara Brae, which is open for tours. It is a Bolshevik souvenir captured by one of this blue-blooded family during the North Russia Intervention in Murmansk during the Russian Civil War. History, like geology, is everywhere — and delightfully unpredictable.

Larwood 2015 participantsFinally, here is a group picture of our 2015 Larwood Symposium participants in Stromness. A most congenial and fun group! Thank you very much to Joanne Porter and Jen Loxton for organizing such a spectacular meeting.

 

Exploring Caithness, Scotland

June 19th, 2015

1 Thurso coast viewTHURSO, SCOTLAND (June 19, 2015) — After meeting in the morning for our 2015 Larwood Symposium, most of the participants then went on a field trip in the region around Thurso in the Caithness district, northern Scotland. Above is a view of the Thurso coast at low tide.

2 Dunnet Head lighthouseOne of the places we visited was Dunnet Head, the most northerly point in mainland Britain. The lighthouse is shown above.

3 Dunnet Head viewThe rocks in this part of Scotland are as austere as the rest of the country. This is the Old Red Sandstone, a Devonian unit found widely in Great Britain. It was deposited under mostly terrestrial conditions, and includes sediments from rivers, lakes, sand dunes and wadis. It splits easily in this part of Scotland into flat slabs called flagstones, which are used for buildings, walls, and tombstones.

4 Dunnet Head flowersThere are beautiful flowers on the windswept slopes of Dunnet Head. If I can, I’ll identify these later and add the name to this post. [Caroline Palmer did us the service: Armeria maritima (Thrift). Thanks, Caroline!]

5 Dunnet Head flowers 2For some reason purple is the most common flower color today. [Caroline identified this as Silene dioica (Red Campion).]

6 Dunnet Head orchidThis is a delicate little orchid I found sheltering behind a wall. [Ah, I made a classic mistake. Caroline points out that this is not an orchid, but a damaged Red Campion (as above). My perspective in this photo gave it a misleading orchid-like appearance. Always a lesson!]

7 John OGroats signJohn O’Groats is the most northeasterly point of mainland Britain. The small village here is 876 miles away from Land’s End in Cornwall, the most southwesterly part of the country. Apparently this is a big deal.

8 Paul Patrick John OGroatsHere we see a typical activity of bryozoan workers: checking fish traps for encrusting colonies. Paul Taylor is on the left and Patrick Wyse Jackson on the left. Paul looks superficially well-dressed, but he’s wearing Crocs on his feet.

9 Old Man of Hoy 2In the evening our party boarded a NorthLink ferry and sailed to Stromness. On the way we passed a sea stack known as the Old Man of Hoy. This erosional feature appeared some time after 1750, and like all coastal rock formations, it is destined to fall into the relentless waves.

10 Stromness from hotel windowFinally in the late evening we made it to the harbor in Stromness, Orkney. This is the view from my window in the Stromness Hotel. The white and blue ferry can be seen in the upper left. We settled in for the night to resume our meeting in the morning.

Wooster Geologist in Scotland

June 18th, 2015

1 Thurso streetTHURSO, SCOTLAND (June 18, 2015) — My long train trip from Scarborough was successful yesterday. I arrived in the dark (or what passes for darkness this far north) and had a long walk from the train station to my hotel. My introduction to Scotland was a driving rain with high winds, so I arrived at the hotel soaked through. These photos, then, are from this morning with much better weather.

2 Thurso seaview 061815This is the very Scottish view from my hotel into the North Sea. The ferry to Orkney departs from the small harbor of Scrabster to the left.

3 Weigh Inn ThursoHere is my hotel. Last night I found it on the outskirts of this small city in a rainstorm.

We had our first sessions of the 2015 Larwood Symposium today at the Environmental Research Institute in Thurso. I was very pleased to give my talk in the morning so I can relax for the rest of the meeting.

Next »