East Lomond EarthCache
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East Lomond, otherwise known as Falkland Hill, is arguably the most distinctive feature in Fife’s landscape. It’s shape clearly indicates it’s past history – it was once a volcano!
There are several hills in Fife which were also volcanoes – West Lomond and Largo Law to name but two - however it is Falkland Hill whose volcanic form remains most pronounced, with it’s steep conical top standing proud, overlooking the Kingdom below.
East Lomond and the other small volcanoes in Fife were active for a short time approximately 300 million years ago, however the geology of the Lomond Hills is much more complex than just that of volcanic activity.
Together, the peaks of East and West Lomond comprise the Lomond Hills. These lie at either end of an escarpment consisting of sandstone, limestone and quartz-dolerite. From the south the escarpment rises gradually to a 350m high plateau between the two hills, however to the north of the escarpment, this plateau drops steeply.
East and West Lomond have survived 300 million years of erosion mostly due to the presence of a hard layer known as the “Midland Valley Sill”. A sill is formed when molten rock (‘magma’) is forced between layers of existing rock. The hot rock is held tightly between these layers. Somewhere off Norway, 305 million years ago, magma pushed through layers of rock as far as Central Scotland. Here it cooled to form a massive structure underground - 150 metres thick in places and extending over 1,600 square km. Known as the Midland Valley Sill, erosion has exposed it in places, generally around the edges and it is this which forms the prominent steep slope to the north of the Lomond Hills. The Sill rock is quartz-dolerite, and it is harder than the sandstone and limestone which lie around it here. The edge of the sill protected these softer rocks enabling them to survive 300 million years of erosion. If you have walked to the summit from the west, you will be walking on top of the Sill where the path steepens above Craigmead. At one point there would have been hundreds of metres of sandstone, limestone and mudstone above here but they have been eroded away by water, wind and ice over the last 300 million years.
If you go to the viewfinder at the top of the hill, you will be standing on a feeder pipe of the extinct volcano. 10 million years after the Midland Valley Sill formed, molten rock forced itself through the Sill to the surface, creating ash and lava cones hundreds of metres high. When the volcanoes began the process of becoming extinct, magma and other debris cooled and solidified inside them to make ‘plugs’ in the pipes. Both East and West Lomond are the eroded remains of two of these plugs. The volcanic cones which would have surrounded the plugs are long gone.
At the above co-ordinates you will find an outcrop of rocks which have columnar jointing. This occurs in areas of volcanic activity, and typically takes the form of straight, parallel-sided columns with between 3-7 sides. The most famous example of columnar jointing is the basalt columns to be found at the Giant’s Causeway in Northern Ireland – where the rocks are in a colonnade form. Surrounding you here, the columnar structure of these rocks is less obvious, the rocks lie in different planes, they are irregular and fractured – these type of columns are known as entablature.
Columns form as a result of stress when molten lava from volcanic activity cools down. As the lava contracts, cracks form. Entablature is thought likely to happen when fresh lava is cooled down by water.
The co-ordinates should take you to the south west edge of this rocky outcrop. Look for the large flat section of rock which slopes downwards. This rock is criss-crossed with large and small cracks.
In order to log this earthcache you must complete the tasks below and email the answers to me through my gc.com profile. Please do not post your answers in your logs.
Answer the following questions:
(1) Which compass direction does the flat surface of this rock slab face?
(2) Estimate the length of the flat rock slab down the slope.
(3) Estimate the angle that this flat rock slab lies at, from vertical
(4) Look at the outer edge of this flat rock slab. Estimate the average height of this edge.
The above information was adapted from the following sources:
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