Weekend Field Trip to 17th-19th September 2010 Led by Martyn Bradley ( University)

This weekend field trip to Eastern Warwickshire was devised to show us the geology of the vale of the upper Avon around Warwick and Royal . We would look at the solid geology, Triassic, Jurassic and Quaternary rocks of the region. We would also look at late Quaternary surface features (such as the fabled “Lake Harrison”) and consider the work of local geologist Professor Fred Shotton, whose research led to establishment of the Wolstonian stage of the British Pleistocene. This was an excellent weekend, thoroughly enjoyed by everyone who attended.

Pauline Kirtley begins the account....

Saturday 18th

The day began sunny and bright, with those staying at the B & B having had a hearty breakfast. A few hiccups early that morning - not helped by Tom’s and my diversion the night before travelling to Warwick - but a fabulous supportive group overcame all. With Guy driving his chariot accompanied by Tim and Julian, they collected Martyn and the hard hats. We met at the first quarry location on the south side of the Avon Valley, Waverley Wood Farm Quarry. Location 1 - Waverley Wood Farm Quarry (436234,271810)

Waverley Wood Farm Quarry is a Quaternary sand and gravel extraction site, just south of village. It lies in the valley of the ancient Bytham River. In early Quaternary times, the Bytham River flowed northeast and east to the Norfolk Coast. Here, Fred Shotton did some extensive work on the glacial drift, leading ultimately to this becoming the type location for the Pleistocene Wolstonian stage.

We donned hard hats and jackets, their vividness accentuated by the brilliant sunshine. John Green, Quarry Manager, explained the excavation of the river sand and gravels and how the area would eventually be restored back to its natural level. Gravels that had been taken from Waverley Wood were now in an area that was a land raised site. He suggested that we recycle, put rubbish back as hills, rather than in holes. It was quite exciting standing on Carboniferous quartzite pebbles, which had been brought down by glaciation and worked by the Bytham River. Amongst the pebbles, hand axes had been found. The rounded pebbles were from the Bunter Pebble Beds, Staffordshire. Budleigh Salterton beds came from the south, from Brittany. We were told that on the M6, near Keele, there was an exposure of the Bunter pebble beds. Ice had brought them down and they were then further rounded by rivers.

Figure 1 Guy with fossilized wood.

Martyn explained that the site exposes (at the base of the excavation) impermeable rocks of the Triassic, Mercia Mudstone Group. These are overlain by 2 m of gravels and sands ( Sands), then a till (Thrussington Till) on top of the gravels. The paleoflow direction (northeast) is readable from sedimentary structures in the sands.

John showed us a photograph of an elephant bone – 13 inches across. This is currently in Warwickshire Museum. The quarry has yielded several important finds, including teeth, and the bones of a straight-tusked elephant. These were found in highly fossiliferous channel fills below the Baginton sands/gravels. Palaeolithic finds include several quartzite hand tools.

We walked for a while through Bubbenhall Wood, then along tracks to the nearby .

Mike Moores takes up the story.....

Location 2 Ryton Pools Country Park (437226,272515)

The group entered the Ryton Pools Country Park from the south access road and immediately came to Pagets Pool (see information board Fig. 2).

Martyn explained that the park had the same sequence of Thrussington Till as the previous quarry (Waverley Wood Quarry) and the pool was set on Mercia Sandstone. It was lower than the previous pool but it was not known why. The opposite side of the pool originally had a clean face but regrettably was now overgrowing. This rather hid the original stratigraphy as this was the boundary of the original quarry and hence not showing landfill.

The Ryton Pools Country Park had been last excavated in the early 1960s and was then landfilled and areas left to produce the pools and the Country Park in the 1980s.

Figure 2 Pagets Pool Information Board

Some parts of the site were Woodland Trust, Bird Hides and a Butterfly Park, however we did not have time to visit these as time was tight and coffee beckoned with a loo stop at the Park’s Visitor Centre. We then made our way out of the park towards our cars but used the opportunity to observe the reinstated areas on the way.

The area has been excellently reinstated to parkland and paths and an example of this was the path between hedgerows which, although less than 20 years old, looked hundreds (see Fig. 3). We stopped at a viewpoint and looked North/North East towards and the valley we would be visiting in the afternoon. The area immediately in front of us had been regrassed and was being grazed as if it had been there for centuries. Figure 3 Path and Hedge in Ryton Pools Country Park

As we left, we managed to mingle with a group of about 20 ramblers who were heading in the same direction. A good bit of chatting and comments were made especially as we were all carrying our hard hats and reflective jackets.

Location 3 Lunch in Wolston village (441245,275530)

After a few abortive attempts to go to pubs in the village green most of settled on the benches on the green and had a sandwich lunch from the local Deli or Co-op. There was an interesting picture board showing the importance of Wolston and its association with the internationally recognised sequence of Wolstonian deposits established by local geologist Professor Fred Shotton of University.

Figure 4 The group Studying the Wolston Information Board

During lunch we watched a man walking back and forth along the bank of the village stream, trailing a long stick in the water. Guy suggested he might be punting, but this was later dismissed when he stopped but did not drift away. He was removing litter from the stream.

After lunch, Tom Miller continues the account....

Location 4 Wolstonian Sequence Excavation Site SSSI (440998,273115)

A short distance to the south of Wolston (about 1 km), towards Stretton-on-Dunsmore, lies Knightlow Hill. On the northern slope of Knightlow Hill there are the remains of an excavation that attempted to expose the important Wolston Sand/Clay and Baginton Sand beds sequence, beneath the Dunsmore gravel. This was an attempt to show and conserve the sequence as a SSSI. A later re-excavation by the Quaternary Research Association (QRA) took place in 1989 and managed (with difficulty) to reexpose the upper 6 m of the section, just revealing the Wolston Sand Beds. Since then, conservation has proved too difficult and dangerous to achieve and the site remains as a grassy hollow. Martyn took us there after lunch and we examined the hollow while Martyn described the heroic attempts by the mechanical digger to achieve the desired result.

Figure 5 The Failed Wolstonian Sequence Excavation Site

What a shame that this important stratigraphic sequence is no longer there to see.

Julian Chard then carries on...

Location 5 Fenny Compton Canal (443133,253267)

Martyn led us to the Wharf Inn on the A423 and down onto the tow path by the Oxford Canal. Following the canal to the left we came across an open field. Here a bench feature of the field on the far side became apparent. This sparked conversation about the presumed Lake Harrison and the evidence collected that it once existed, ‘Does Lake Harrison hold water?’

A bench is a feature that is a wave-cut platform that marks the upper limit of a previous shoreline.

On the hillside in front of us, there was a clear downward slope that took the shape of a beach.

We then walked back along the canal towards the pub. Every few meters we would pause long enough to peer across to the other side of the canal and study the bench feature to see if it was still present and if so were there any differences to where we began. We walked all the way till we were standing on a bridge over the entrance to a marina. Here Martyn Bradley collated the evidence and our thoughts on what we had seen and showed us the two sides to the argument. One was that the lake did exist but because of the height variance in the benches along the canal’s far side, it may have occurred in different stages of glacial melting. However the lack of depositional evidence suggests that these benches could have been formed by glacial erosion rather than the shoreline of a lake. This lack of evidence in turn could be misleading as during the time in between present and time of the glacier, the shoreline deposition may have been weathered away.

After a well deserved cup of tea at the pub it was decided that there was just not enough evidence to support the theory that a lake existed at this point. Figure 6 Is this Fred Shotton’s Wave-cut Platform?

After this pleasurable interlude, we set off for our final location of the day, the Burton Dassett Hills. Pam Konieczny takes up the story......

Location 6 Burton Dassett Hills (443133,253267)

After we arrived at Burton Dassett, Martyn took us to Windmill Hill, one of several marlstone capped hills that stand above a flat plain of Lower Lias clays; part of the Charmouth Mudstone formation.

A renovated 14th century beacon survives, constructed from marlstone quarried in the Burton Dassett Hills. On examination of the building blocks we observed that the marlstone was a sandy, oolitic limestone rich in oxidised iron, which gave the stone its brown appearance. Remains of brachiopods and belemnites were visible.

We then walked down a shallow dip slope over a 100ft series of grey sandy silts, part of the Middle Lias Bytham formation, where the terrain was defined by hawthorn bushes and poor grasses. Then the terrain changed abruptly to wet land with patches of sedge and much longer grasses. On sampling, the soil was found to be heavy clay and we were standing on the boundary of the permeable Middle Lias and the underlying Lower Lias clays.

Figure 7 Marlstone Knolls - Burton Dassett Hills

The marlstone outcropped as knolls, through the lias. Martyn pointed out the marlstone junction with a silt unit beneath. The junction of the silt on the underlying, less impermeable lower lias was easily recognised on the outer slopes by a spring line.

This was our last location of a long day out in Eastern Warwickshire. We returned to Warwick and enjoyed a fine evening meal with Martyn and his wife Julie. Sunday 19th

The next day, Martyn took us on a fine tour of Warwick Town. This took in many of the sites and locations shown in the official Warwick Town Trail published jointly by the Warwickshire Geological Conservation Group (WGCG) and the Geologists Association (GA).

We set out soon after breakfast and made straight for the River Avon, to Banbury Road Bridge near the Castle.

Location 1

14th century Warwick Castle itself was built from the light yellow Bromsgrove Sandstone and the Sandstone. However, the castle gatehouse contains blocks of oolitic limestone from the Cotswolds.

Figure 8 River Avon and Warwick Castle

After passing through the castle gate we immediately entered the Sunken Lane connecting the castle gatehouse to the castle courtyard. This is a sheltered lane, hewn from the Bromsgrove Sandstone. Well-defined cross- bedding in the walls of the lane show the Bromsgrove Sandstone as a desert river deposit.

We left the castle grounds via Castle Street and continued up the hill to St Mary’s Church. This has many weathered Arden Sandstone blocks in the base of its tower.

Figure 9 St Mary’s Church – Arden Sandstone Blocks

There are many fine buildings along Old Square, Swan Street and Puckeridge Lane that have interesting building stones in them. We spent a good while looking at each before moving off to our second location of the day, at Rock Mill Lane, Milverton, between Warwick and Leamington Spa. Location 2 Rock Mill Lane (430119,266297)

At Rock Mill Lane, Milverton, beside the River Avon, there is a small exposure of the Arden Sandstone ‘skerry’, used locally as a building stone. We had seen this used in the base of the tower of St. Mary’s Church, favoured for its load bearing qualities. This rock is triassic, from the Mercia Mudstone Group. It can be red or green depending on the oxidation level of its iron content.

Figure 9 Arden Sandstone - Rock Mill Lane

We left the site at Rock Mill Lane and set off for Leamington Spa, our third and final location for the day.

Location 3 Royal Leamington Spa

We had a very good lunch in the Royal Pump Room Museum, then set off on a building stones tour of Leamington Spa. Again, this took in many of the sites and locations shown in the official Royal Leamington Spa Geology and Building Stones Trail published jointly by the WGCG and the GA. Martyn did not follow the trail exactly, but took us to most of the key locations centred on/in the , the Victorian Riverside Gardens, and all along “The Parade”.

Like Warwick, Royal Leamington Spa has many fine buildings but has a more modern face. The city centre shops have a rich assortment of igneous, limestone and travertine cladding.

On taking the spa waters at the fountain, we were all very surprised at how salty it was. Strange how our predecessors had developed the notion that this was somehow healthy to drink. Enthralled, but really quite tired now after such a full weekend, we thanked Martyn heartily and set off for home.

Our special thanks also go to Pauline Kirtley who did such a good job of setting it all up, despite all of the difficulties involved.

Text Pauline Kirtley, Pam Konieczny, Julian Chard, Mike Moores and Tom Miller

Photos Tom Miller