A Geology Field Trip at Otley Chevin

 

Passing the rock face at the Yorkgate Quarry

Following on from a great day out in Rotherham, where I explored the historic architecture, building stones and geology of Wath-upon-Dearne and West Melton, I returned to Otley Chevin in West Yorkshire for a field trip with the Sheffield U3A Geology Group – having previously undertaken a recce 12 days earlier with the Group leader Paul. 

 

The road network between Leeds and Otley

On that occasion his Sat Nav took us all around the houses and, even though I had again suggested that we should rely on old fashioned navigation with a road map - after taking another grand tour around the east side of Leeds – we arrived at the East Chevin Quarry car park 15 minutes late and discovered that everyone else had just followed the road signs. 

 

The rendezvous at East Chevin Quarry car park

Our first stop was the outcrop of the supposed tidal laminites, where I was still not convinced of this explanation without seeing evidence for the very rapid crustal subsidence that must take place for these to be preserved and, as often on our field trips, there was a good debate. 

 

An exposure of supposed tidal laninites

 

Paul, who was our leader for the day, led the group to one of several viewpoints that overlook Otley and proceeded to talk about the glacial history of Wharfedale and the evidence that can be seen to support this in the valley below. 

 

A viewpoint overlooking Wharfedale

Arriving at the next location, a former quarry in the Addingham Edge Grit, on this occasion I managed to find the sculpted marker stone No. 2 by Shane Green, which depicts a river delta. The very coarse sandstone, as with the other formations in the Millstone Grit Group, was laid down as part of a huge river delta system at the edge of a landmass that was near to the equator during the early part of the Upper Carboniferous Period. 

 

Marker stone No. 2

As often happens when accompanying the field trip leader on the recce, when I undertake a thorough investigation of the geology, I often find that I spend more time taking photographs for use in the report on the day, which the leader usually writes, or leading the way rather than listening to what is being said to the rest of the group.

 

At the Vacca Wall

 

We had discovered that the signposting at the west end of the route on the geology trail was not very clear and, on this occasion, we took another route up past marker stone No. 5, which depicts the large scale cross-bedding that is a feature of the large slipped blocks of Doubler Stones Sandstone that litter the upper slopes. 

 

Marker stone No. 5

Continuing to location No. 4, where there are good examples of soft sediment deformation structures and fossilised tree branches, we were running later than planned and one of our members was making it clear that we were well past our usual lunch time. 

 

Location No. 4

 

When planning and undertaking recces for several field trips, as I recall quite vividly from the first field trip that I led to Green Moor, I have discovered that it is not always easy to get the timing of the lunch break right, when it is desirable to find a place that has somewhere good to sit and ideally sheltered – to protect us from the rain, wind and sun. 

 

Lunchtime

Continuing with our walk after lunch at the Yorkgate Quarry, we stopped to find the traces of tree roots that can be seen as dimples in the bedding plane of the Doubler Stones Sandstone, as well as looking at the fireclay seatearth and the overlying thin seam of the Morton Banks Coal. 

 

In search of rootlets, fireclay and coal

We then our made our way along the escarpment to Surprise View, which is at the crest of The Chevin and is formed by the very coarse and pebbly Doubler Stones Sandstone. With a car park serving this part of Otley Chevin Forest, this is very popular with general tourists and is served by a rather pricey ice cream vendor. 

 

The approach to Surprise View

 

With several members taking advantage of this, I set about trying to find a sample of pebbly sandstone from one of the well worn paths, which I didn’t yet have in my rock collection and, to my great appreciation, one of my friends found a fractured quartz pebble for me - of a size that I had only seen before in the Chatsworth Grit. 

 

Specimens collected at Surprise View