Granophyre.

Granophyre.

This specimen of Ercall granophyre is as it's name suggests,  from Ercall quarry in the Shropshire hills. It's age is about 560 million years,  placing it in the Ediacaran period.  At the exposed nonconformity,  the pinkish coloured  porphyritic granophyre is overlain by the lower Cambrian wrekin quartzite.  The quarry is an SSI site, and no hammering is allowed,  so  the specimen was collected from loose pieces on the quarry floor. It is not an easy rock to identify, needing a microscope and thin section to observe the quartz and feldspar intergrowth. The pinkish colour is very striking, and the photograph is as true to colour as I can get.


Agglomerate.

Agglomerate.

This specimen of rhyolitic agglomerate was collected fro Forest Glen Quarry car park, at the foot of the Wrekin in Shropshire. The rocks in the quarry are Uriconian and of debated age. possibly Precambrian or early Cambrian. The agglomerate specimen is typical of an exposure in the quarry. The fragments of volcanic rock are purply and reddish in colour, and indicate deposition in a pyroclastic flow.  


Conglomerate.

Conglomerate.

This specimen is from an outcrop of conglomerate in the Hafren forest, near Llanidloes, Mid Wales. The age of the rocks are Silurian, and they are in the Landovery epoch. The outcrop is markedly graded, with material at the top being very fine, and at the base very rubbly. The rock specimen is 10 cm. and the conglomerate layer is about 2 metres in depth. The conglomerate is very rich in quartz, with quite a number of large rounded pebbles at the base.and with smaller, often fractured pebbles towards the top.


An introduction.

An introduction.

Over the years, I have picked up quite a number of rock specimens. a good number of them have been picked up on Club field trips. The specimens are housed in my back garden in a large container, together with my minerals, also listed on this site. I am not an expert, but an enthusiastic amateur, but I do try and give accurate information to the best of my ability. Thanks for looking.


Concretion, Dolfor, type one.

Concretion, Dolfor, type one.

Concretions are plentiful in the mudstones of central Wales. Some sites produce distinctive concretions, which can be particular to that site. This concretion is from a small roadside quarry just north of Dolfor, Nr.Newtown, Mid Wales. I have collected three similar specimens from the site. Each one has distinctive marks all around the base, which are compatible with the sedimentary layers from which they came. The age of the rock is Silurian. There is another type of concretion from this quarry which is very distinctive, and this will be placed on this site in the near future. For definitive concretion information, see Tony Thorp's article in the Silurian magazine No. 1 which can be found on this website.