Geology

There is significant geological importance across the site due to the topography of the land and the history of the underlying rocks. Much of The Chevin is also designated as a Regionally Important Geological Site (a map showing the RIGS kept at The White House). The rock formations that underlie The Chevin are of the Carboniferous age, more specifically they belong to the Millstone Grit Group consisting of gritty sandstones interbedded with shale formations which were laid down as sediment around 315 million years ago (when The Chevin was part of a tropical river delta). The gritstone layers forming The Chevin were deposited by a river with strong and shifting currents. These have given rise to a distinctive crossbedding which can be seen in many gritstone outcrops such as those at Caley Crags on the Danefield side – on some of these rocks traces of burrowing activity from arthropods and molluscs can be seen.

About 310 million years ago continental collisions crumpled and stacked up layers of rocks in this area. Older, deeper layers of rock were arched upwards and younger overlying layers of Millstone Grit sloped away southwards, forming a long escarpment from Harewood (in the east) to Addingham (in the west).

During the last Ice Age (1-2 million years ago) there was a great thickness of ice covering most of Wharfe Valley. Later, as this ice retreated, there were some large landslips affecting the north face of the Millstone Grit escarpment, which exposed a section of fossil-rich mudstones and limestones known as the Otley Shell Bed  – today known as Great Dib Wood SSSI. Virtually all marine groups of animal fossils are represented within the Otley Shell Bed including: brachiopods; bivalves; gastropods; ostracods; corals; polyzoa; and fish fragments. It is also of particular importance because it is amongst the youngest series of rocks to contain a now extinct group of animals known as trilobites.

The Chevin contains a nationally important geological feature on the White House side called Great Dib Wood Site of Special Scientific Interest (SSSI). Under the Wildlife & Countryside Act (as amended) there is statutory duty on LCC to ensure the SSSI is managed in a way to be classified as “In Favourable Condition” by English Nature. Great Dib Wood SSSI is just less than 1ha. in size and is in an area not easily accessible to the public. Its main significance is as a scientific resource and therefore it is important to prevent too much vegetation growing on the features of interest (which would obscure them).

(from Chevin Forest Park Local nature Reserve Management Plan 2016-2026)

Please contact us if you wish to see the RIGS map, as The White House is not open to the public.

Downloads

• Brief account of the rocks and landscapes on the Chevin (PDF) ,
• Article by the West Yorkshire Geology Trust from November 2010 (PDF)
• Interpretation board at Surprise View is available (PDF)

Click on the leaflet covers for .pdfs of the Chevin Geology Trail leaflet