Geological Excursion to Yorkshire Dales
The Yorkshire Dales is remarkable for its geomorphological formations. One can reach the place by train arriving to upcountry village of Giggleswick. The station was originally known as Settle station, being renamed after the completion of the Settle-Carlisle Railway. From Settle one can observe the Cowside Back river, and it is here where one can first notice limestone covered with rank vegetation, including heather and bilberry. (Gilbert 2005)
The local landscapes, including scars, caverns, caves, rivers and waterfalls owes its origin mostly to glacier movement, when huge masses of ice presses the earth surface leading to formation of fanciful landscape forms. The geological history of Yorkshire can be perfectly traced with Thornton Force. Located on the river Twiss, the waterfall appeared as a result of glacial diversion that shape a “cap rock” where waters of the river fall from about 330 million years old Carboniferous Great Scar Limestone back to the original river valley belonging to the Lower Ordovician Ingleton Group that is about 500 million years old.
(Waltham, 2007. p. 80) Figure 1. Uplift of ice creating Thornton Force (Thornton Force) Thornton Force is a part of a larger geomorphological construction known as The Craven Fault. The Craven Fault consists of three portions including the North Craven Fault, the Mid Craven Fault, and the South Craven Fault. A line formed by those faults creates a boundary between the limestone rocks of the Higher Dales and a more gentle landscape of the western and southern parts of the Yorkshire Dales.
The spectacular geological features of the Craven Fault include limestone geological unconformity and the mentioned Thornton. The area was once a bottom of a subtropical sea, that can be demonstrated by examination of the southern portions of Craven Fault where limestone hills were once coral atolls in the warm waters of prehistoric ocean. (Waltham, 2007. p. 82) A notable element of the Craven Fault landscape is the Norber Brow composed of erratic Silurian Austwick Gritstone derived from Crumack Dale. Erratic blocks covering the Great Scar limestone appeared as a result of ice-flow.
When large masses of Devensian ice melted away the blocks remained standing on the limestone basics which are now used to indicate the original glacier bottom. (Peter McLaren Donald, 2006, p. 454) One of relatively small local sites is the Globe-flower wood which is a minor portion of Yorkshire Wildlife Trust. The area is periodically flushed with lime-rich spring waters deriving from junctions between Silurian and limestone rocks. Consequently the land is a marsh meadow. The flora is composed of globe flowers, wood cranesbill and melancholy thistle growing on pastures, mixed with groves formed of birch, sycamore and willows.
(Peter McLaren Donald, 2006, p. 451) Close to the Globe flower wood lays the Unimproved pasture – vast area of acid calcareous grassland supporting populations of wild plants including moonwort, autumn gentian and limestone bedstraw. The grassland here is touched by human influence as some portions of the pastures are used as hay meadows. The place has recently attracted the attention of ecologists resulting in affirmation of an Action plan aimed to arrest the depletion of unimproved lowland meadows (See: Action plan. Unimproved pastures).
Foredale Quarry is an interesting site where one can observe clearly visible tilted flagstone beds of limestone. This includes the famous Angular unconformity site located at the Lower Palaeozoic Craven inlier. The underlying rocks are attributed to Horton Formation while the upper formations belong to Lower Carboniferous age. The Horton geological forms are presented by Studfold Sandstone Member made of fine-grained turbidite sandstone with disseminations of volcanic clay (bentonite) coming from distant volcanic explosions. (Peter McLaren Donald, 2006, p. 452)
The Colt Park Wood is recognized as a site of special scientific interest since it is one of the few surviving sites of the area that once covered most of the limestone highland presently being the Ingleborough National Nature Reserve. The below limestone rocks are about 300 million years old, while the above geological forms, including karst caverns owe their origin to glacial erosion resulting from glacial rifts. Ice pressure created notable exposures called pavements. Damp and windless microclimate also enables growth of moss, lichen and flowers.
Deep beneath the Ingleborough Hill lays the White Scar Cave system – on of the largest in Great Britain. This is a snow cave excavated by streams, most probably out of caverns in the limestone during the ice melting period. It now includes thousands of stalactites – formations shaped by mineral deposits brought by water. Similar to it is the smaller Great Douk Cave, however, it is remarkable for its entrance hidden behind the waterfall. (See: Marshal D. Rust D. , 1997) Rich deposits of limestone in Yorkshire were used by men since prehistoric times.
The lime kilns that are still found in Yorkshire exemplify the technology of the XIX century used by local people for construction. As time passed kilns were covered with vegetation and became a part of the local landscape. Moreover, houses in local villages like Arncliffe were made of limestone for centuries, turning the villages into a part of the same landscape. The design of the kilns differs enormously, although they have some similar features including the lining of the bowl with sandstone slips or fire-bricks and alignment of the kilns.
Remarkably they are now attracting attention of local natural heritage protectors as examples of interaction between nature and industrial civilization. Once being tools of man’s domination, they are now giving shelter to some of the local spices, including mammals, invertebrates, mosses, lichens and ferns. (Limekilns Report) References 1. Gilbert O. , Goldie H. , Hodgson D. , Marker M. , Pentecost A. , Proctor M. , Richardson D. The ecology of Cowside Beck, a tributary of the River Skirfare in the Malham area of Yorkshire. 2005.
Available from: http://www. field-studies-council. org/documents/centres/malham/reports/Cowside%20Beck%20report. pdf [7 May 2009]; 2. Waltam T. 2008. The Yorkshire Dales: Landscape and Geology. Crowood Press; Illustrated edition; 3. Peter McLaren Donald, Duff, P. J. Brenchley, Rawson P. F. (2006) The geology of England and Wales. Geological Society. 2nd Illustrated edition; 4. Marshal D. Rust D. 1997. Selected Caves of Britain and Ireland. Cordee 5. Action plan. Unimproved Pastures.
National Park Authority Available from: http://www. peakdistrict. gov. uk/bap6_2_up. pdf [5 May 2009]; 6. Singleton T. , Potter C. , Askew D. Limekilns of the Arnside/Silverdale Area of Outstanding Natural Beauty (Program Report) Limestone Heritage Project. Available from: http://www. arnsidesilverdaleaonb. org. uk/limestone/converted/docs/Limekilns. pdf [5 May 2009]; 7. Thornton Force. Craven & Pendle Geological Society. Available from: http://www. kabrna. com/cpgs/countryside/ingleton/thornton_force. htm [7 May 2009];Sample Essay of RushEssay.com