Rock facts, water nas­ties and ‘de­sire lines’

Trail (UK) - - CONTENTS - Ed Nichols, via Face­book

QIt’s easy to spot rocks of dif­fer­ent colours around the moun­tains, but what gives them their dif­fer­ent shades?

Paul says The colour of a rock is de­pen­dent on the min­er­als it’s made up of. Rocks orig­i­nat­ing in the earth’s man­tle (such as olivine) are of­ten green­ish in colour. How­ever, when a rock is ex­posed to the at­mos­phere it is chem­i­cally ‘weath­ered’ and of­ten changes colour. Red­dish colour­ing, for ex­am­ple, is of­ten due to ox­i­di­s­a­tion (rust­ing) of iron min­er­als on the rock’s sur­face. There is a gen­eral trend for rocks to be­come some shade of grey as they weather, but there are al­ways ex­cep­tions and va­ri­eties of colour.

Stain­ing on rocks at Yeast­yrigg Gill in the Lake Dis­trict.

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