PPL The Tynemouth Dyke, one of a Tertiary swarm emanating from the Isle of Mull, is exposed on the shore almost immediately adjacent to the north side of  Tynemouth Pier. Exposures can also be seen in the cliff leading to the pier where horizontal hexagonal jointing can be seen.

XPL The section shows laths of plagioclase feldspar (dark grey to white) and pyroxenes (yellow, brown, blue & red). The centre shows an infilled vesicle of  carbonate. Some of the feldspar laths are seen to be tangentially arranged around the vesicle as a result of its expansion on release of pressure. 


Notice how the dyke margins show contact alteration. 

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