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Kynance cove

The Lizard Peninsula in Cornwall is the most southerly point in of the British mainland. The geological features of this area are unique and similar geological features can only be found in a few other regions in the world. It’s not surprising that people visit the area whilst staying at their cottages in Cornwall. The exposed rocks of the Lizard complex are the best known preserved example of ophiolite. An ophiolite is an exposed section of the oceanic crust. This exposure happens when two tectonic plates shift and one moves underneath the other causing the underneath plate to sink into the earth’s mantle and lifting the mantle to leave parts of it exposed.  The serpentinite and metamorphic rocks on the Cornish Lizard peninsula are comprised of parts of exposed earth’s mantle and parts of a former oceanic floor. The serpentine rocks which span nearly twenty miles in Cornwall are a rare geological find.

Much of the Lizard peninsula consists of the serpentinite rocks, which are green and reddish in appearance.  The serpentinite rock formations are the exposed and metamorphosed remains of the earth’s mantle that were exposed through the shifting of tectonic plates known as subduction.  Some sections of the serpentinite grow foliage while other sections are covered in amphibole, which are black colored rocks. The serpentinite rocks form the Kynance Cove cliffs, these rocks are distinctive to this area.  The Kynance Cove is known as one of the magnificent and beautiful stretches of coastal land in the South West.

Parts of the Lizard peninsula are the remains of an ancient ocean floor that was pushed to the surface when giant plates shifted and collided. At the lizard peninsula the boundaries between the Earth’s crust and mantle are visible. At one side you can see the serpentinite rock which is altered rock from the earth’s core. In a transition area, known as the basalt dykes you can find basalt and gabbro, which are the remnants of magma in the earth’s mantle, and at another nearby section you will see the gabbro stone which is a remnant of the oceans crust. Gabbro is a form of magma that has solidified. The Lizard Peninsula is one of the few places Moho is visible, Moho is the boundary between the Earth’s crust and mantle.

Remnants of geological features and occurrences can be traced in some parts of the lizard peninsula. The hornblende schist, found in the northern and southern areas of the lizard peninsula near serpentinite rock, is a remnant of basaltic intrusives that have metamorphosed at least three times.  Basalt is formed in three ways, erupting oceanic hotspots, in mantle plumes, and shifting oceanic divergent boundaries.

Oceanic hotspots are areas where an eruption occurs on the ocean floor the eruptions can become frequent and strong enough to form an island over time.  Mantle plumes are the upwelling of a hot section of rocks in the earth’s mantle.  Most of earth’s basalt however is produced as a result of plate tectonics below the ocean floor. This is where convection or heating occurs; and as the hot rock melts away the divergent boundaries pull apart and an eruption occurs. This method of the formation of basalt is what most likely occurred in the Lizard Peninsula region.

The various rock formations and remnants of geological occurrences found at the Lizard Peninsula in Cornwall are a treasure trove of discovery for Geology and Earth science students. A visit to this astounding geological feature during your North Cornwall holiday will give you a peek into the world deep below the earth’s surface.

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