Inverness Castle has been often rebuilt and replaced over the last thousand years. Often the focal point of dissension, the darker curtain walls date back from the times of Bonnie Prince Charlie and the Jacobite Uprising of the mid-18th century. For the purposes of this earthcache however, we are more interested in the 1836 edition of Inverness Castle.
With it's courthouse front and later prison section in the rear, the Castle was designed by noted architect William Burn. The primary material used in it's construction is Tarradale sandstone, used extensively over the region.
Sandstone is an example of clastic sedimentary rock. It is formed as grains of sand accumulate in rivers, pile up in position and are pressed down by the compression of further layers. The material used for Inverness Castle comes from nearby Tarradale Quarry, which is part of the Raddery Sandstone Formation and of Devonian Age (between 419.2 and 358.9 million years old).
Another geological process that can dictate the appearance of sedimentary rocks (such as sandstone) is lamination. The influence of things like grain size and organic material can be seen in the small difference of built-up lines across each rock. A common case of lamination in sandstone is wave energy, which leads to grain size seperation. Water will also deposit minerals, such as calcium carbonate, iron oxide and quartz which can alter the colour of the resulting material.
To log this earthcache, please email me (or message using Geocaching.com) answers to the following. Logs without the accompanying email/message may be deleted in time but feel free to log the cache before my reply!
1) Get as close to the Castle as the current refurbishment will allow. Describe the pattern on a singular block and compare it to the next one along. Are they exactly the same or different?
2) If they are different, could you explain why?
3) If the sandstone at Inverness is of mid-Devonian age, how many million years old is it? A rough figure will be fine.
4) What chemical compound gives the sandstone it's pinkish colour?
5) OPTIONAL: Post a photo of your GPS at Inverness Castle.