3 Kings EarthCache
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Perhaps the most striking feature of the town of Cullen is the series of railway viaduct arches. The arches frame some of the best views of the town and its surroundings; most magnificent of all as you come down the hill from the town is Cullen Bay with the isolated sea stacks known as the 'Three Kings', which rise up from the sands. They are said to be grave markers of 3 Norse Kings who died at the Battle of Bauds in 962 ~ The first mention of Cullen in Scottish history was in 962 when King Indulf was killed by the Norwegians (and/or Danes) at the mouth of the river Cullen and referred to as the Battle of the Bauds ~ "Atween Coedlich and the sea, There lies Kings' sons three." Legend has it that within the vicinity, a Scots, Danish and a Norwegian King are buried, marked by the three isolated rocks within Cullen Bay and named the "Three Kings".
Sea stacks are formed from the continuous pounding of the waves on a headland wears away weaknesses in joints, crevasses and softer rock faster than the harder and more solid rock, enlarging any gaps already there and eventually forming a cave. Sometimes a cave also forms on the other side of the headland and the two eventually meet in the middle forming an arch, or one cave over time erodes all the way through. We now have an arch. Even with the formation of the arch the erosional processes do not stop. The waves continue to widen the gap until the rock above can no longer be supported. At this point, part of the top portion gives way forming a blow hole, and then as the entire top portion falls away into the sea below leaving the furthest away arch support standing alone in the sea as a sea stack. But it doesn’t end there as the relentless seas continue pounding away and the stack is worn down to a stump.
Only two of the three stacks are in the tidal zone, the third is nestled in behind one of the buildings on dry land but long ago was also in the sea as this is now a raised beach. (visit link)
There are some amazing rock formations along this stretch of coast,( at the far end of the golf course is The Whale's Mouth - a slanted arch of rock) produced by the deeply folded beds of Cullen quartzite, an impure quartzite with bands of pelite containing garnets. This is a metamorphic rock which was originally quartz sandstone. This rock is part of the Cullen Quartzite formation which is seen along the coast between Buckie and Cullen and is some 2,400m thick and dates from the Neoproterozoic Era 1,000 to 541 million years ago.
These rocks were folded when the ancient continents of Laurentia and Avalonia collided during the Caledonia orogeny. They later became exposed at the surface where sea and weather eroded the structure seen today. Quartz-bearing sandstone is converted into quartzite through heating and pressure usually related to tectonic compression. Rocks can be divided into three main groups, sedimentary, igneous and metamorphic.
Sedimentary rocks are laid down as particles of material such as sand or mud and then hardened by compaction and lithification into sandstones, siltstones, mudstones and limestones. Fossils are often preserved in these rocks.
Igneous rocks crystallise from magma originating deep beneath the Earth’s surface and may be extrusive (i.e. lava flows at the Earth’s surface) or intrusive (emplaced within the Earth’s crust, below the surface).
Metamorphic rocks are older sedimentary,metamorphic or igneous rocks that have been altered by changes in temperature and/or pressure. New minerals grow in response to these changes and their composition depends on the composition of the original rock, and the temperatures and pressures that affect it.
How is metamorphic rock formed?
Metamorphic rock is formed underground through a process that changes a rock's molecular structure due to pressure and/or heat and/or chemical reactions. A metamorphic rock forms from a parent rock called a protolith. Depending on conditions, a protolith can transform into any metamorphic rock. Because protoliths are capable of undergoing vast changes, identifying them is sometimes difficult for geologists.
Under extreme pressures, such as between two colliding tectonic plates, the minerals of a metamorphic rock group together and align to form foliation, which appears as stripes in the rock. Alternatively, highly heated areas, such as near magma chambers, produce vastly different metamorphic rocks. Another area for metamorphism is at a subduction zone where oceanic plates collide with and bend under continental plates. Because these high-pressure areas are near the ocean, they are cooler and produce different metamorphic results.A protolith may change a number of times before reaching its final metamorphic stage. For example, gneiss may begin as shale that turns into slate, phyllite, schist and finally gneiss.
So how does sandstone change into quartzite?
Sandstone changes into quartzite through the pressure and heating that results from tectonic compression inside the orogenic belts. The sandstone transforms into quartzite gradually and with little change at a mineralogic level. When the transition from sandstone to quartzite occurs, the quartz grains in the sandstone recrystallize and form sedimentary structures of quartz crystals. Quartzite is a hard metamorphic rock that is usually grey or white, but may take other light colours depending on the impurities present in the sandstone. This rock occurs often in areas with high-pressure metamorphism. The rock is resistant to chemical weathering, and its almost pure silica content leads to little to no vegetation on quartzite ridges.
Be aware of the tide ~ if it is in and you cannot get to 2 of the Kings, there is always the 3rd one safely on land
To claim this earthcache, please send the answers to the questions below to us by email /messenger - do not post in your online log. Your log may be deleted if these criteria are not met. Educational guidelines for Earthcaches are set by Geocaching.com and GeoSociety.org (Earthcache) and have to be adhered to.
1 What chemical is the main component of quartz?
2 Estimate the height of the largest stack .
3 In which compass direction have the sedimentary layers been tilted 'downwards' towards to, and at approximately what degree tilted from the horizon at zero degrees?
4 What colour are the rocks here, and why?
5 Look closely at the rocks, you should see the individual quartz crystals and sand grains, describe the size,colour and shape of them. Are the grains in the rocks the same size as those on the beach, if there is a difference, why do you think this is ?
While not compulsory, photos of your visit are always good to see
Enjoy your visit and happy caching
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