In the northeast of England, Northumberland’s geology contributes significant landscape features and includes a mix of sedimentary, intrusive and extrusive igneous rocks from the Palaeozoic and Cenozoic eras. The Cheviots Hills are formed from Devonian age volcanic rocks and a granite pluton, whilst rest of the county is characterised largely by a thick sequence of sedimentary rocks of Carboniferous age. Both Permian and Palaeogene dykes and sills intrude the area and the whole is overlain by unconsolidated sediments from the last ice age and the post-glacial period. The Whin Sill is visible across the county and impacts greatly on Northumberland's character.
Fell Sandstone, a Visean (Lower Carboniferous) formation, outcrops in an arc stretching from south east Scotland through Northumberland into the Brampton district of Cumbria. The formation is between 240 m and 300 m thick and has a particularly uniform physical characteristics; it is mostly made up of well-sorted, crumbly, fine to medium (0.125-0.25mm) grained cross bedded sandstone, with no significant calcareous (chalky) content. Crossbedding, that is layers of sandstone at an angle to the main layer are commonly seen and is in evidence in the area surounding the cave and inside the cave site. The sandstone units are often separated by thin red and green micro- crossbedded argillaceous silts, a clay type deposit, carried by running water, with occasional thin bands of sedimentary rock containing pebbles up to 25 mm in diameter. The outcrop forms barren, heathery moorland hills in a distinctive craggy escarpment around the Cheviot Hills, with a gentle dip slope which follows the angle of the underlying strata or rock layers towards the east, south-east and south
The Northumberland Sandstone Hills are a major natural region that lies entirely within the English county of Northumberland. They curve across central Northumberland in a series of distinctive skylines of flat-topped ridges, craggy outcrops and northwest facing scarps and which provide panoramic views of both the Cheviots and the coast. These ridgetops and upper slopes are covered with heather and grass moorland. They lie not far from the coast of Northumberland and the region is listed as a National Character Area. The region covers an area of 72,694 hectares (280.67 sq mi), beginning at Kyloe in the north and running in a strip roughly 10 to 15 kilometres wide and parallel to the coastal plain as far as Alnwick where it changes direction to head southwest via Thrunton Wood, Rothbury Forest and Harwood Forest to the area of Throckington and the River Rede passing over the highest peaks in the area, including Tosson Hill (1,444 feet (440 m)) in the Simonside Hills.The Sandstone Hills play an important role in the recharge of the Fell Sandstone Aquifer; the quality and quantity of the water are important to the area for the supply of water locally and to northern Northumberland.
To log this EarthCache, go to the published coordinates and examine the surrounding cave and large stones. Then answer the following questions via email or through the Message Centre. Do not include answers in your log. Any log will be deleted after 1 week if no answers are sent
1. Observe the stone that is present in and around the cave, what type is it? Describe the texture and appearance of the stone surface both inside and outside the cave.
2.What is the main colour is the stone inside the cave?
3. What is the approximate circumference of the pillar, at the narrowest point, holding up the roof of the main cave?
4. 08/04/2022 As per the updated guidelines, a Photo can now be used at part of the logging task. You have two options in regards to the photo:
(a) Take a photo of yourself in the vicinity of GZ.
(b) If you prefer not to take a photo of yourself please take a photo of a personal item in the vicinity of GZ
NB: The only way to reach the cave is on foot, following the St Cuthbert's Way trail. The easiest access point is from the National Trust car park at Holburn Grange, beside the farmhouse. The farm is located on a minor road midway between the B6353 and the B6349.
(Whilst you are here take a look at the carvings, they are very interesting. We wanted to focus our questions around the carvings but weren’t allowed under EarthCache regulations)