At 248m above sea level, Charnwood Beacon is the second-highest point in Leicestershire. It is a popular local beauty spot for walkers and families, but not many people know of its geological significance. The rocks under the feet of those visitors are in fact older than the Rockies, the Alps and even the Himalayas: these comparative youngsters are all under 80 million years old, but the rocks of Beacon Hill were formed 600 million years ago – some of the oldest anywhere on earth.
The rocks were formed during a period of violent volcanic activity, from ash cooling and sinking into the ancient sea which covered the surrounding area. The crater of the volcano is thought to have been located near the outcrop named High Sharpley, 4 miles NE of Charnwood Beacon. Around 560 million years ago further volcanic activity forced these rocks upwards to form a mountain range several thousand feet higher than its more modest height today. The angled layers in the summit crags show how the original horizontal layers of rock have been tilted upwards by the immense volcanic pressure, and weathered away to form the characteristic Charnwood Forest landscape.
There are many types of rock to be found on the Beacon: agglomerates, formed from fragments of lava; tuffs, made from layers of solidified volcanic ash; and slates, formed much later from compressed mud layers over the older volcanic rock. To log this cache, please complete the following:
1) Identify (with the help of the ‘spoiler’ pictures if you wish) examples of laminated tuffaceous rocks from around the summit of Beacon Hill. Describe what they are like: how do they feel and what colour(s) are they? How are they different from other rocks you may have seen, for example limestone, slate, gritstone? Photograph your examples and upload them with your log if you wish.
2) Find a good example of the tilted layers in the crags. What angle are they at now, compared with their original horizontal position? What is the steepest angle from the horizontal that you can find on the summit?
3) To prove you have visited the site, email us the co-ordinates of the tilted layers near the summit(please don’t put this in your log).
Co-ordinates are given for the two car parks: the Upper car park is closest to the summit area and has picnic tables and WCs. The Lower car park is approx 1 mile from the summit and has WCs. Both are pay-on-entry, £2.50 per car (April 2010). Please see the Leicestershire County Council website link on this page for the car park opening times.
We really enjoy reading cachers' logs but don't always manage to reply to emails very quickly. Please feel free to log your find but please also be sure to email us as soon as possible. If we don't receive an email or there are problems with your answers we will contact you and ask you for further information. Any logs without emails within 2 weeks will be deleted in accordance with Earthcache guidelines.
In celebration of the 90th birthday of the great naturalist and geologist, Sir David Attenborough, who grew up in Leicester, we are dedicating this Earthcache to him. Sir David described his early visits to the forest as "the highlights of my Leicester boyhood" and he enjoyed visiting the Beacon to search for fossils.