Microgabbro on Carrock Fell

We also found microgabbro on Round Knott just before we reached the summit of Carrock Fell. According to the book "Exploring Lakeland Rocks and Landscapes" published by The Cumberland Geological Society, the darker layers are augite and the paler layers are plagioclase. Gabbro is a plutonic rock that cools a long way underground so grows large crystals. The idea is that the augite crystallised first and sank to the bottom, depleting the magma of iron and magnesium. That made the liquid over-rich in aluminium and calcium so plagioclase crystallised out. This restored the original chemical balance and the cycle repeated, hence the layers. A further note to my wondering about granophyre or microganite for the summit: it is called granophyre in the book The English Lake District by Pearsall and Pennington.