An accessible EarthCache that will bring you to a seafront landmark in the Sunny Seaside town of Scarborough.
The irony of this location is not lost on me for those who have tried to decipher my Earth Cache logs as I am not the brightest one when doing these types of caches ;)
You will undertake a geology lesson as you visit this scenic location.
To log this EarthCache, send me your answers via email or the message centre.
Types of Rocks
There are three types, Igneous, Metamorphic and Sedimentary.
Igneous rock is formed through the cooling and solidification of magma or lava. An example of this is granite.
Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form".The original rock is subjected to heat and pressure, causing profound physical and/or chemical change. An example of this is marble another example is slate.
Sedimentary rocks are types of rock that are formed by the deposition and subsequent cementation of that material at the surface and within bodies of water. Sedimentation is the collective name for processes that cause mineral and/or organic particles to settle in place. The particles that form a sedimentary rock by accumulating are called sediment. Examples of this rock are sandstone and limestone.
A few common rocks and identifying features
Basalt is a dark igneous rock, and is made up of fine crystals, because it cooled rapidly after it came out of a volcano. Basalt does not contain any bedding planes. It is unsuitable for buildings since it is very hard and difficult to fashion into blocks for building, it can however be used more crudely for building simple walls.
Granite This is an igneous rock made up of noticeably different crystals of different coloured minerals. Granite may contain crystal structures of different sizes. it cooled slowly below the surface. you won’t be able to identify fossils because it forms from the cooling down of molten material, therefore never contained organisms in it. It doesn't contain any bedding planes as it formed from cooling magma. This is very good building material since it has no linear weaknesses.
Marble Marble is a metamorphic rock, It is formed from limestone that has been subjected to intense pressure underground due to tectonic movement or through being subject to extreme heat. This rock is generally white with different coloured veins running through it. It is a very tough rock and would feel very smooth even after years of exposure to the elements.
Slate is a metamorphic rock. It is a fine grained rock of sedimentary origin. It is waterproof and extremely durable, Slate occurs in a variety of colours from pale to dark. Due to its durability it has often been used for tombstones and memorial tablets.
Limestone is a sedimentary rock. A common building material especially in ancient times due to the decorative look of the rock and its propensity to being easily carved. This is often a light coloured rock, but other limestones may be variously coloured including darker colours. which suffers from chemical weathering, as a result of acid rain. It may contain bedding planes and many variety of fossils including corals, shells and marine life.
Sandstone is a sedimentary rock, it can be grey, red or yellow in colour. You will be able to identify the bedding planes which are lines that run all the way through the rock, where different seasons or catastrophic events have altered the composition of the deposits for a short time. The rock will be quite durable but feel rough to the touch and small grains will come off when you rub it vigorously.
Bedding planes are the layers of sedimentary rocks that are distinctly different from overlying and underlying beds of different sedimentary rocks. Layers of beds are called strata. They are formed from sedimentary rocks being deposited on the Earth's solid surface over a long periods of time. Bedding planes come in different forms as the rocks have moved over time. Often bedding planes are visibly different in colour from each other.
Physical weathering
Physical weathering is caused by physical processes such as changes in temperature, freezing and thawing, and the effects of wind, rain and waves.
Temperature changes : When a rock gets hot it expands a little, and when it gets cold the rock contracts a little. If a rock is heated and cooled many times, cracks form and pieces of rock fall away. This type of physical weathering happens a lot in deserts, because it is very hot during the day but very cold at night.
Wind, rain and waves : Wind, rain and waves can all cause weathering. The wind can blow tiny grains of sand against a rock. These wear the rock away and weather it. Rain and waves lashing against a rock can also wear it away over long periods of time.
Freeze-thaw : Water expands slightly when it freezes to form ice. This is why water pipes sometimes burst in the winter. You might have seen a demonstration of this sort of thing - a jar filled to the brim with water eventually shatters after it is put into a freezer. The formation of ice can also break rocks. If water gets into a crack in a rock and then freezes, it expands and pushes the crack further apart. When the ice melts later, water can get further into the crack. When the water freezes, it expands and makes the crack even bigger.
Questions
1. At the posted coordinates, take a look at the second window from the left as seen on the picture. Please look carefully at the colour, texture and general appearance of the marking underneath the window.
1a. What do you think these are?
1b. What do you think causes this?
2. Still looking at the window, lower down the left of it, please can you tell me about the appearance of that part of the stone? Can you see any visible evidence of the effects of the weather on the rock ?
2a. Describe this and explain what you think has happened ?
2b. What do you think causes this?
3. What stone do you think the building is made from ?
3a. Why do you conclude this ?
3b. Why do you think this material was used ?
3c.What are the disadvantageous of using Sandstone for buildings?
4. If you run your fingers over the surface, what does it feel like?
5. (Optional) Feel free to take a photo of yourself in front of the main door to prove that you are not an armchair solver. I am not often sat at the PC, and to save you waiting possibly days for the thumbs up, feel free to log, with a pic to prove you were there, I love a cheesy smiley selfie. If there are major problems with the answers you send, I will let you know, otherwise take it as answers accepted :)
