Trewern Brook
Also within
Geology & landscape
Geological Period: Silurian · Rock Type: Mudstone
Description
Description Trewern Brook is the type locality for, and the best section through, the entire Trewern Brook Mudstone Formation. In the Long Mountain area this formation represents the Wenlock Series, one of the main divisions of the Silurian System. High in the formation occurs the Glyn Member, a calcareous, shelly horizon within a thick, laminated mudstone sequence. When these strata were laid down, the Long Mountain area lay on the eastern edge of a deep ocean basin occupying most of Wales, whilst shallower ‘shelf’ seas extended eastwards over the Midlands. Fossil organisms characteristic of both deep and shallow marine environments can be found in the rocks of Trewern Brook, enabling detailed comparisons to be made between the two environments. This is of great importance in the accurate dating of Wenlock rocks from Wales and the Midlands. This is the best section in the Wenlock Series in this important position between the Welsh basin and the Midlands shelf.