INTRODUCTION

As this is an EarthCache, a type of Virtual Cache, there is no physical container here. 

This EarthCache adheres to the principles and ethics of geocaching and leaves No Trace.

Welcome to one of very favourite childhood haunts. Below is me. The sign has moved back since the first picture was taken.

There is a very nice Adventure Lab here too.

ACTIVITY

1. Please describe the texture.

2. Please describe the overall colour of the sandstone in this particular area

3. Why does this look different from the overall colour of the castle? 

4. Please tell what sort of weathering you can see, and tell me what you think is causing the blemishes, and how.

5. As this is an EarthCache, Under the 2010 guidelines, a photograph can be requested. 

Please log the EarthCache and include your photograph taken at the sign as shown.

Please send me a message and you will get one confirming your answers as soon as I am able.

As long as you have done your best, and proved that you were there, it should be fine.

DUFFUS CASTLE

Duffus Castle is now in ruins, but it was once the strongest fortress in Scotland.

Originally, this would have been a wooden castle built in the 1100s on the top of a mound of earth. This motte and bailey design was to lift the castle off the boggy plain. There is a large enclosing moat.

This motte and bailey design was to lift the castle off the boggy plain. There is a large enclosing moat. The castle was rebuilt in stone in the early 1300s. However, the castle was abandoned in 1705 and fell into disrepair.

Duffus Castle was a fortress–residence for more than 500 years, from the 1100s to the 1700s. The stone castle we see today was built in the 1300s, replacing an earlier timber fortress.

However, the castle was abandoned in 1705 and fell into disrepair.

Fall being the operative word. You can clearly see one side of the castle has slipped down the embankment and has come to rest at an angle. Whether this happened in one earth-moving landslip or gradually over time is anyone’s guess. It’s stable enough now to walk inside and get an angled view of the Laich of Moray through one of the tiny windows.

Parking is free, and there is a snack and drinks hut in the car park. 

A WEE GEOLOGICAL LESSON

Duffus Castle is made of local sandstone.

Characteristics of Sandstone:

Sandstone is a sedimentary rock composed mostly of sand grains made of quartz and feldspar.
Sandstones are formed when sands are eroded from one part of the Earth surface and then are transported by water or wind to a different location. There the sediments are deposited in layers.
Overtime these sand layers are buried deep under the Earth’s surface and become slowly cemented together into hard rock. (That is why you can often see layers in sandstone rocks)
Sandstone can come in all sorts of colours (brown, tan, yellow, brown, red, gray, pink, white and black)

Three Common Colours of Sandstone

Yellow Sandstone
This is a highy silica rich stone and is fine grained. Portland stone falls into this category and this type of stone is a popular building material since it is easily carved and holds its shape over long periods of time.Yellow Sandstone has been used for domestic construction and housewares since prehistoric times, and continues to be used. Sandstone was a popular building material from ancient times. It is relatively soft, making it easy to carve. It has been widely used around the world in constructing temples, homes, and other buildings. It has also been used for artistic purposes to create ornamental fountains and statues. This type of stone can be very smooth to the touch and as water runs over it can be 'polished' to an almost marble finish. This will be blonde in colour and can be bleached white in direct sunlight

Grey Sandstone
Often called mudstone, grey sandstone is a very fine grained stone. This type of stone is usualy smooth and has no defined lines in its composition. Also, mudrock is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm (0.0025 in) with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the appearance of fissility or parallel layering. This finely bedded material that splits readily into thin layers is called shale, as distinct from mudstone.

Red Sandstone
Red is the rough side of the family of stones. It is made up of large grains and is a poor buliding stone since it usually has very obvious lines where different layers have been deposited and tends to split easly along these fissures. If you are looking at red sandstone you will be able to see clear lines across the rock where softer parts of the rock have 'washed away' during ersosive episodes. Because of the hardness of individual grains, uniformity of grain size and friability of their structure, this type of sandstone is excellent materials from which to make grindstones, for sharpening blades and other implements. Non-friable sandstone can be used to make grindstones for grinding grain, This stone will be rough to the touch and will have a definite redish hue.  

WEATHERING

Physical Weathering is caused by the effects of changing temperature on rocks, causing the rock to break apart. The process is sometimes assisted by water. It is likely that these stones, which have been in place for almost 85 years, have been affected by freezing and thawing which has caused layers to flake off from the surface. The also have been smoothed over the years by wind and particles blowing in the wind causing the smoothing of the surfaces.

Biological Weathering is caused by living organisms that can contribute to the weathering process in many ways. The particulat type of biological weathering is from algae and lichens that produce chemicals that help break down the rock on which they live, so they can get the nutrients they need. Lichen produces organic acids that can chemically weather the sandstone, leading to further discoloration and erosion. Lichens can trap moisture, which can enhance physical weathering and potentially lead to flaking or crumbling of the sandstone. The growth of lichen can change the appearance of sandstone, sometimes covering up or altering its natural colours.

Chemical Weathering is caused by rain water reacting with the mineral grains in rocks to form new minerals (clays) and soluble salts. These reactions occur particularly when the water is slightly acidic. Chemical weathering (especially hydrolysis and oxidation) is the first stage in the production of soils. The black discoloration due to deposits of chemicals have over time become part of the sandstone surface.

EarthCache placed with the kind permission of Historic Scotland