WELDED TUFF (IGNIMBRITE) - Chelmsford, Essex
« backWELDED TUFF (IGNIMBRITE)
470 million years old
Roxwell Quarry, near Chelmsford, Essex
Welded tuff, or ignimbrite, was formed by a violent volcanic eruption which released massive amounts of extremely hot volcanic ash. A fast-moving, incandescent and highly destructive mass of hot particles is produced which is known as a pyroclastic flow or nuée ardente (French for 'glowing cloud').
Welded tuff, or ignimbrite, was formed by a violent volcanic eruption which released massive amounts of extremely hot volcanic ash. A fast-moving, incandescent and highly destructive mass of hot particles is produced which is known as a pyroclastic flow or nuée ardente (French for 'glowing cloud').
Volcanism of this kind occurred in what is now North Wales during the Ordovician period and the rocks there are evidence of these volcanoes.
This specimen originated in Snowdonia and was brought to Essex by the River Thames during the Ice Age when the river’s headwaters drained the mountains of North Wales.
This is a good example with two cut faces.
Click on a picture for a larger image
Size: 6.5 x 5.5 x 4.5 centimetres
Weight: 244 grams
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