CWM TON SSI – Glascoed People & Places

CWM TON SITE OF SPECIAL SCIENTIFIC INTEREST (SSSI).

This Site of Special Scientific Interest (SSSI) is a geological feature that is a rarity in the UK, of particular interest to geologists.

It’s an outcrop of rocks that runs on either side of Glascoed Lane, from Ton farm (near St. Michael’s church, Glascoed) to Cwm farm.

It’s described as “an important geological site providing excellent exposures of Silurian rocks, formed about 410 million years ago. The rocks exposed consist mainly of limestones, representing the upper part of the Usk Limestone, overlain by siltstones. The Usk Limestone was traditionally regarded as equivalent in age to the Wenlock Limestone by recent work has led to a revision of this interpretation. These limestones and silts now appear to be Ludlow in age, significantly younger than the Wenlock Limestone and separated from it by an important break in the geological record. This site is therefore of considerable importance in the study of geological events during the Silurian Period at about the junction of the Wenlock and Ludlow series.” (The Countryside Council for Wales: Site of Special Scientific Interest Citation).

Here is a map showing the location of Cwm Ton SSI, from the Natural Resources Wales website.