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Showing posts from March 20, 2025

Geology highlights: Penzance to St Ives

One of the stand-outs for me about this coastline is the spectacular geology - it’s incredibly varied, with some of the oldest formations I will see until I get up to Scotland. Here is a little summary of the geology that has stood out to me so far. Penzance and Mount’s Bay Mainly  Devonian slates and sandstones  with more recent  alluvial deposits  and  beach sands in the bay, , and the beautiful  St Michael’s Mount  a granite outcrop connected to the mainland by a tidal causeway. Mount’s Bay to Porthcurno  M etamorphosed mudstones and slates  apparently called killas appear along side  granite intrusions  from the larger Land’s End Granite mass which I crossed on the second day. We started to notice striking black “dykes” - exposures of  contact metamorphism , where the granite intruded into the sedimentary rocks. I hadn’t been aware of these before but they are called  hornfels . There are also  quartz veins  ...

Day 6: Porthtowan to Holywell (14 miles)

Starting at 10am, a steep climb out of Porthtowan brought me back onto the high cliffs overlooking the beach.  Heading over the tops Wheal Charlotte came into view set against the blossoming gorse - a classic sight.  It still looked some distance off, and before long I was heading down the zig zags to Chapel Porth valley.  I was taken by surprise as I climbed around the corner from the valley to see Wheal Charlotte close by with the turquoise sea and rolling waves below.  Onward now for pretty easy walking on the tops, wanting to keep pace so I could meet Martin if possible walking out from Perranporth. Again I seemed to reach St Agnes Head with the coastguard station above the path much faster than I thought.  I was trying to work out whether the birds I was seeing were all gulls or if there were kittiwakes among them. I’m not confident yet of identifying them, though I am of fulmars. Winding my way down to Trevaunance Cove, I was surprised by a deep crack open...