In 2009 Essex county council resurfaced the Brentwood High street and replaced tarmac pavements with reconstituted granite slaps. This was designed to create “a new visual aspect for the high street”.
However soon after the street was installed residents criticised the new paving in the local press; claiming it was like an ice rink.
However, there is a lot of other rock on Brentwood high street and this EarthCache takes you to look at two different examples of rock being used. These rocks have been there a lot longer than the high street paving installed in 2009.
The lesson aims to teach you:
- Examples of how rock can be used in building construction.
- Consider differences in properties of different rock types.
Stop 1 – Larkin’s Drinking Fountain
This drinking fountain and horse trough was presented to the town in 1910. This shows us that in 1910 the horse was still a major form of transport. The Larkin family that donated the foundation also donated the playing fields in Ongar road.
The trough is made of Cornish granite from Bordmin Moor. The bowl of the drinking fountain made of a different colour granite from Sweden. This is called ‘Balmoral’ There are smaller grains within the drinking fountain – these are feldspar crystals.
- How does the colour of the Balmoral Granite differ from the Cornish Granite?
- Apart from colour compare the difference in quality between the two types of granite? (include the difference in feldspar crystals).
- Which of the two rocks is less resistant (more susceptible to erosion) based on what you can see; what evidence is there?
Stop 2 – 16-18 High Street (currently occupied by Peacocks -was Argos)
On the posts of the building there is Italian serpentinite; also known as serpentine. This is a metamorphic rock. Some of its characteristic appearance is caused by the presence of water being involved when it metamorphosed (being subjected to great heat and pressure). This serpentinite is similar to the the serpentinite on Lizard peninsula Cornwall.
The picture below is of Serpentinite from the Lizard peninsular in Conrwall:
Using the picture above compare the serpentinite on the front of 16-18 High Street to the rock from Lizard Island Cornwall.
4. What are the similarities and differences between the two types of rock?
When you log the cache please also email or message the answers to me - however you don't need to wait for a response before logging.