Why does geology matter in the study of natural history?
When using geological observations in association with botanical ecology some simple rules apply: 1. Old Red Sandstone (O.R.S.), which makes up the bulk of the island, is mainly silica which is insoluble and impermeable. O.R.S. tends to give rise to nutrient-poor, often wet and anoxic soils of low pH (acid moorland and bogs). 2. The volcanic rocks that were intruded through the bulk of the island as vertical plates (dykes) mostly contain lower levels of silica than the O.R.S., but basic minerals are more plentiful and diverse. They tend to be relatively soluble in acidic water (e.g. rain) so that minerals leach out and become available to terrestrial organisms as nutrients. Less acidic soils form on the dykes than on the O.R.S. and they probably have some influence on conditions in the marshes that form on the raised beaches between them. 3. “Raised beaches” refers to flat areas that are found all around the island margin. They are ancient beach platforms with a wave cut cliff inland,
