Ross on Wye Old Red Sandstone

We went on a South Wales GA trip to the Ross on Wye area with ORS expert John Davies. The morning's localities were in and around Ross itself and then, after lunch, we went a few miles west, first to Goodrich Castle and then to Wyastone.
John has a wealth of information about the ORS which he has investigated and mapped extensively, in particular looking at similarities and hence correlations between the facies here and in Pembrokeshire.
First stop was in Brampton Abbots where there are exposures in a sunken lane. John explained that the outcrop is wide on the map because the dip is so shallow.

Shallow, south dipping thinly bedded sediment of the Senni Fm in the lane section

Rooting around in the rockery on someone's bank looking for a bit with more
pebbles in! This is the overlying Lawrenny Cliff Fm and has many exotic
pebbles: quartz, rhyolite, greywacke, various igneous rocks and sedimentary
clasts. Very rounded, and the provenance indicates a source to the north

The dip steepens closer to Ross, possibly because of a fault structure that ties in with the Caledonian Lower Usk Valley fault system.
Just a little way down the lane we came to an exposure of the Lawrenny Cliff Fm on a junction. The was a coars, angular sandstone with a scattering of rounded pebbles and more angular clasts. It is cross-stratified, dipping to the S-SW which ties in with interpretation of bars in a braided river moving downstream.

The Lawrenny Cliff Fm in Brampton.

Moving back towards Ross we paused by a bridge over the A40/A449 where that road goes through a deep cutting. When the road was built there was excellent exposure and a series of detailed drawings were made of the sedimentary structures (Allen 1974) but the exposures are now weathered, netted and vegetated so less can be seen.

The A40 road section (Allen, 1974)

The ENE end of the section

Most of the section is now not visible. Also the road is now too busy to allow easy examination

Back through the centre of Ross we came to the well known "Ross River Cliff" exposure below the Royal Hotel. The cross stratified rocks here belong to the New Shipping Fm which lies over the Lawrenny Cliff Fm. and from which it is separated by a mudstone. Strong currents produced planar cross-stratified sets, separated by stillstands during periods of lower flow. Again there are some rounded pebbles, and also large, discoid mud clasts.

The New Shipping Fm in Ross River Cliff. 

Ross River Cliff: planar stratified sediments separated by packets of cross-
stratified sandstone

From here we headed up to the terrace of the Royal Hotel from where there is an excellent view of the country to the north: the ridge formed by the Lawrenny Cliff Fm, then lower ground occupied by the Bryn Melyn Mudstone, before the ridge of New Shipping Fm sandstone on which we are standing. John has correlated these beds from his type areas in Pembrokeshire to this area.
After lunch we moved on to Goodrich Castle which is built on an exposure of New Shipping Fm rocks along the same ridge. From the track to the castle we stopped to look at the view to the SE where a mudstone valley (at the top of the New Shipping Fm) separated us from a ridge formed by two beds of conglomerate, the lower has large quartz pebbles but has not been identified. The upper, which caps the hills, is of the Upper ORS.

View SE from Goodrich Castle. Mudstone valley in the foreground, then conglomerate caped hills on the skyline

Goodrich Castle from the ditch. The builders made use of natural rock exposures

The square Keep is earlier than the round towers and curtain
walls. It is also built of a more grey-green sandstone
possibly Tintern Sandstone which could have been brought
upriver by barge

Close up of Keep walls

At first floor level in the Keep is the original doorway with round topped, Romanesque arch.
This was later converted to a window when a ground floor entrance was created.

From here we continued SW to Wyastone where we crossed from the New Shipping Fm onto the Lawrenny Cliff Fm which we saw in a drive section by the house.
A final stop was to have been at Craig y dorth, further down the Wye valley but although we found the grid reference (nothing to see there!) we temporarily lost our leader who had overshot the turning and Jan and I decided it was time to go home!
I should just explain that John Davies is in the process of writing up his work and the names he has currently given to the formations could change!