Sunday 5 Nov

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Having looked at glacial erosional features on Saturday, we set off on Sunday to look at areas of morainic drift. Our first stop was to look at the Tandle Hill – Shaw Moraine. At the car park of Tandle Hill Country Park, we were joined by some OUGS members who live nearby, including Norma Rothwell, whose local knowledge proved invaluable later in the day. Dick and Simon explained that, as the Devensian ice sheet retreated southwards off the Rossendale Plateau into the Manchester embayment, it oscillated. At times, it halted and stagnated, then re-advanced, forming push-moraines before retreating once more. Recent mapping has identified three distinct moraine ridges in the area; between Tandle Hill and Shaw, between Rainsough and Chadderton Heights and between Whitefield and Heywood, the Pilsworth Moraine. We planned to look at the first two, which have been linked to the Heinrich 2 Event at 22kyr BP. (Figure 1)
 

Figure 1. Sketch map of Lakes and Moraines identified in Southern Rosssendale/North Manchester area.

A walk through the beech woods took us to the top of Tandle Hill. From there, we looked down the steep slope of the edge of the moraine to the south and west. There were good views to the east of the ridge to Shaw and to the north, the Rossendale Plateau dissected by valleys including the Irwell. The ground to the north of Tandle Hill slopes gently towards the Rossendale Plateau and is very irregular. Sand and gravel would have been dumped here as the ice retreated. As we drove away to our second location, we noted that we were going down the steep front of the Tandle Hill Moraine. (Photographs 8,9,10 and 11)

Our second location was Chadderton Fold Park. The River Irk flows through here and joins the Irwell to the west. We crossed the Irk and walked up to a flat bench above the present river. On the way, we investigated – with help from the dog – an exposure of not very well bedded sand and pebbles including , Permo-Trias sand from Cheshire and Staffordshire and pebbles of Borrowdale volcanics, Eskdale granites, Haslingdon Flags, siltstones and coal from Coal Measures exposures. (Photograph 12)

From the bench we could see the Chadderton Moraine with its steep south-facing slope and gentle slope to the north. Dick and Simon told us that the bench, which was very flat, was the course of a river between two areas of higher ground, the one to the north being the Chadderton Moraine. It was subsequently cut into by the present river. It is all a post-glacial outwash valley, a valley sandur, possibly formed by summer floods in the time of the Loch Lomond Stadial. Here the river Irk has cut down about 10 m. Boreholes in nearby Middleton show that there is about 30 m of sediment in this part of Manchester. 

After lunch at the “Duke of York” – no – “Duke of Lancaster” – no – “Rose of Lancaster” pub, we went to Rhodes. This is high ground to the east of Middleton and about three miles downstream. Here we stood on a bridge over the motorway to have another look at the valley of the River Irk. We had good views of the valley sandur, now built on, between the ridge of moraine to the north and the high ground we were on. To the south, the land sloped imperceptibly down towards the continuous urban area of Manchester. (Photograph 14)

For our last location, Plan A has been to visit Boggart Hole Clough to look at the stratigraphy of the glaciogenic sediments, where they can be seen in the walls of the ravine. It isn’t particularly easy of access. Fortunately, Norma had a Plan B. She knew of another location called Bucks Hill, which was new to Dick and Simon. The stream that comes from Boggart Hole Clough runs past a housing estate before it joins the River Irk. There was a nice exposure in the steep bank opposite the houses. The top surface was the gentle grade leading into Manchester. The upper layer was clay, containing Lake District pebbles. Between that and the streambed were 3 – 4 m of sand. (Photograph 16)

We had a happy half hour playing in the sand after Simon had wielded his entrenching tool to give a clean surface. Lamination and cross-bedding were seen as well as lenses of clay and coarse sand and fragments of coal. The area was probably ponded in a glacio-lacustrine environment. We also managed to disturb a solitary bee that had made its hole in the sand. After tucking it back up, we ended a very enjoyable and interesting field trip. Thanks to all involved in arranging and leading it. (Photograph 17)
 

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