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| *****SWAAG_ID***** | 880 |
| Date Entered | 18/07/2015 |
| Updated on | 21/07/2015 |
| Recorded by | Tim Laurie |
| Category | Geological Record |
| Record Type | Geomorphology |
| Site Access | Public Footpath |
| Record Date | 07/07/2015 |
| Location | Ribblehead; Thorns Gill |
| Civil Parish | Not known |
| Brit. National Grid | SD 775 795 |
| Altitude | 300m |
| Geology | Thorns Gill is a very attractive small stream-cut gorge which, below the old footbridge, respects the line of a former cavern exposed by glacial erosion of the limestone, see photos below. Perched erratic boulders of limestone carried by ice from bedrock origin further east are a spectacular feature of this walk.
One of these boulders shows shallow shrinkage cracking characteristic of episodic drying-shrinking of the shallow sea bed at low tide during Late Carboniferous Time some 280 Million Years ago (Information, John Russell and see photo nos |
| Record Name | Glacial erratics and a fine old arched footbridge at Thornsgill. One of Arthur Wainwright's favourite walks. |
| Record Description | Following in Arthur Wainwright's footsteps, a small party of SWAAG Members explored the limestone erratic perched boulders, the rich vegetation and views of Ingleborough at Thorns Gill, Ribblehead.
Reference: Wainwright, A. 'Walks in Limestone Country.'Eighth Impression.Kendal, Westmorland. Gazette, Kendal. |
| Dimensions | Not more than a couple of miles walking. |
| Additional Notes | To see the flowers at their best, a walk in spring is recommended. |
| Image 1 ID | 6246 Click image to enlarge |
| Image 1 Description | John summons his attentive audience to explain 280mya shrinkage cracks on a limestone boulder- a phenomenal geomorphological phenomenum made plain to all.For details of the cracking,see Image Nos 15 and 16 below |  |
| Image 2 ID | 6261 Click image to enlarge |
| Image 2 Description | Perched boulder, see also photos and drawings in Arther Wainwright's 'Walks in Limestone Country', Section 22. |  |
| Image 3 ID | 6247 Click image to enlarge |
| Image 3 Description | Glacially rounded boulder fluted by water during post glacial time. Inglebrough in the background. |  |
| Image 4 ID | 6248 Click image to enlarge |
| Image 4 Description | John gets close and friendly with an unconcerned glacial phenomenum. |  |
| Image 5 ID | 6249 Click image to enlarge |
| Image 5 Description | John investigates the bedrock to compare the different rock composition. |  |
| Image 6 ID | 6250 Click image to enlarge |
| Image 6 Description | Further erratic limestone boulders on limestone bedrock. |  |
| Image 7 ID | 6251 Click image to enlarge |
| Image 7 Description | The small fern, Wall-rue (Asplenium ruta-mururia) |  |
| Image 8 ID | 6252 Click image to enlarge |
| Image 8 Description | Fluted boulder |  |
| Image 9 ID | 6253 Click image to enlarge |
| Image 9 Description | Fluted boulder |  |
| Image 10 ID | 6254 Click image to enlarge |
| Image 10 Description | Fluted boulder |  |
| Image 11 ID | 6255 Click image to enlarge |
| Image 11 Description | Split boulder |  |
| Image 12 ID | 6256 Click image to enlarge |
| Image 12 Description | Thorns Gill stream follows the line of a subterranean cavern |  |
| Image 13 ID | 6257 Click image to enlarge |
| Image 13 Description | The packhorse bridge drawn by Wainwright, see below |  |
| Image 14 ID | 6258 Click image to enlarge |
| Image 14 Description | Anne and Ric on the Bridge. |  |
| Image 15 ID | 6259 Click image to enlarge |
| Image 15 Description | John explains the origin of the shrinkage cracks |  |
| Image 16 ID | 6260 Click image to enlarge |
| Image 16 Description | Detail of the shallow cracks on the face of the boulder, once a surface of calcareous mud exposed to the drying sun between tides. |  |
| Image 17 ID | 6262 Click image to enlarge |
| Image 17 Description | One of the attractive pools |  |
| Image 18 ID | 6263 Click image to enlarge |
| Image 18 Description | Ash tree |  |
| Image 19 ID | 6264 Click image to enlarge |
| Image 19 Description | |  |
