Introduction to Rocks
About the event
Do you find rocks confusing? If so, this is the day school for you. Come along to learn about the origin, composition and identification of the three major rock groups. Some are surprisingly beautiful! During the day you will be able to practice identifying a variety of rocks specimens.
Rocks are all around us whether they are used as stone in buildings, aggregate for roads or are the foundation of our most loved landscapes.
Only a dozen or so minerals make up the majority of rocks. Unfortunately the various combinations have been given a plethora of names. We shall try to demystify rock identification and classification. The good news is that ‘keys’ are available to identify them.
We shall begin with a brief review of the main rock forming minerals. They will introduce us to the three rock families namely igneous, sedimentary and metamorphic. We shall see how these are related to each other by melting, pressure and weathering.
The rest of the day will be divided into sessions where we study the groups in more detail. Each session will look at the composition, origin and geological environment where particular rocks are formed. For example granites are the ‘signature’ rocks of the continents. They contain quartz, feldspar and mica as the ‘essential’ minerals. Many are formed within the crust by the melting of pre-existing sedimentary rock but others originate from mantle magmas. How can we tell the difference? Similarly what do the minerals in metamorphic rocks tell us about the temperature and pressure conditions of their creation? Do they speak of collision between the Earths plates, of magma intrusion and baking or perhaps meteorite impact?
Sediments too contain hidden messages. What can we learn from the shape of grains or indeed how well sorted they are into different sizes. How are muds created, why are they so tenacious and why are there more muddy rocks in the Lower Palaeozoic than in later periods?
These and many more questions will be answered during the day and you will have the chance to try your hand at rock identification and interpretation using the keys.
Led by Peter Golding, Geologist
Suitable for beginners and improvers