2019 AGM

The AGM was held on 8^th June at the Talbot, Knightwick. The meeting heard a report from the chair, most of which is printed in the Annual Review, an electronic version of which was sent out in mid-June. There are a limited number of hard copies in colour available for £1 (plus postage) and you can also find the review on our website. David Pamment presented the financial report, which was commended for its clarity by the meeting. The meeting re-elected Ian Fairchild and Peter Stevens and elected Peter Bridges at Trustees. Julie Harrald has stepped down as Trustee to give herself the opportunity to do a secondment project with us, during her PhD, about Natural Capital which is how government is valuing the natural environment. Julie wants to establish guidelines for how geoheritage can be valued in this way. More of this in due course.

Following the AGM, Dick Bryant and Ian Fairchild led a group of 17 people on a local geowalk (see map below).

Solid Geology at Knightwick

Knightwick is in an interesting position at the intersection of the Malvern line with the Teme Valley and on the river bank. Dick explained various theories about the history of the drainage during the progressive erosion of the landscape and in relation to glaciation and glacial lakes in particular.

The Teme Valley Geological Society have expressed interest in doing some work on the river terraces to help solve the mystery about when and how the Teme changed its flow direction from westward-flowing (as seen in higher terraces near Tenbury Wells) to eastward-flowing (a river capture event), and some more background is given in the Annual Review. No terraces are visible from Knightwick, but examples are shown on the map in the Annual Review.

The party then walked to the western end of Osebury Rock across the valley at the foot of which Dick pointed out the toe of an alluvial fan at the outlet of the side valley. Permission to examine the outcrop at Osebury Rock had been given by Natural England and the landowner Martin Cross of Coles Farm, Lulsley.

Steep crags of stratified breccia are well-exposed (see photo below), indicating intermittent water flow on an alluvial fan.

Breccia at Osebury Rock

John Payne demonstrated the occurrence of ventifacts (see photo below) – wind-faceted pebbles (also known as dreikanter) indicating the aridity of the depositional setting. The age of this outcrop has been controversial. Originally it was grouped with various outcrops of breccias of late Carboniferous or early Permian age (Haffield Breccia), but the remapping of the area by the BGS led to reassignment to the Triassic by analogy with basal breccia facies beneath sandstones in the Worcester Graben. John Payne pointed out that Osebury Rock was just east of a major fault to the west of which are Silurian strata. The older breccias are not known east of this fault which strengthens the Triassic interpretation.

Osebury Rock Triassic Breccia Ventifact

The group then examined small outcrops of breccia in the fields to the west of Osebury Rock (see photo below). Here there is an obscure, partly faulted contact with red sandstones. These were originally assigned to the Permian, but now regarded as Triassic, directly overlying the Osebury outcrops. In the lane cutting near the top of the hill on the Alfrick road, cross-bedding is seen, presumably of fluvial origin.

Dick explaining breccia to participants west of Osebury Rock

The party then walked down the lane to Lulsley, stopping just short to view the Teme Valley to the east within which there is a distinct terrace, the lowest (and youngest) found in the valley. One-metre contours from Lidar data help to mark the terrace which is just 2 m above the modern floodplain and probably formed in post-glacial times.

To the north west of Lulsley Court is an open stretch of floodplain bounding the Teme. From here there are splendid views (see photo below) of landslips in Triassic rocks across the valley to Ankerdine Hill. Occasionally the A44 has been blocked by landslip events as in 2007. Dick pointed out that the river capture event led to more rapid downcutting of the Teme and this would have led to steeper, more unstable hillsides, promoting landslips which are shown also in the Silurian beds on the southern margins of Ankerdine Hill.