Granite is an intrusive igneous rock, which is formed when magma cools and solidifies under the earth's surface. The rock is composed of a mixture of feldspar, mica and quartz. The colour of the granite will depend on the colour of the components. Feldspar may range from pink, through brown to green. Quartz is generally clear or white. Mica is the dark coloured component that gives granite a salt and pepper appearance.
Dimension stone is rock that has been cut and finished to predetermined requirements and used for either structural or decorative purposes. The size and form of dimension stone can vary from large blocks, to sheets or slabs, to small tiles. Nearly any stone can be used as dimension stone, however the most common types are granite, marble, limestone, and slate. One dimension stone that has been used in many structures is granite.
Adelaide Ground Zero
The granite stone at the listed coordinates was dedicated in 1928. The monument notes "Hereabouts in January 1837, the survey of the city of Adelaide was begun" Nearby, make sure you don't trip over it, is a new marker showing the exact location of zero point zero as set by Colonel William Light, first Surveyor General of Adelaide. Check the crystal size and colour of the granite stone with the plaque. You will need to compare the colour and grain size with the stones at the second waypoint.
The End of Light
The monument at the second waypoint was dedicated in 1905. This monument is the grave of Colonel William Light, first Surveyor General of Adelaide. The vertical monument in the middle of the pond contains four levels of different granite dimension stone, Base/Pedestal/Column/Crown. Please answer the following questions.
-Which specific granite stone is common at both locations? Look carefully at colour, grain size and mica form. Identify the location of this stone in the monument.
-Why do you think other granite stone types have been used in the Light monument?
-What is the variation in elevation between the two locations? How would you measure the difference in elevation? How do you think Light measured the difference?