GREYWACKE - Powys, Mid Wales
« backGREYWACKE
430 million years old
430 million years old
(Silurian period)
Rhayader, Powys, Mid Wales
Greywacke is a hard, dark-coloured rock with poorly-sorted angular fragments of quartz, feldspar, and other rocks in a sandy clay matrix.
It was formed by submarine avalanches that created colossal turbidity currents which churned up the sediment. Such currents are found today in the deep oceans on the edges of the continental shelves, and at the bottoms of ocean trenches.
Size: 8 x 5.5 x 4.5 centimetres
Weight: 183 grams
-8055-p.jpg?v=FB3A7943-01FA-498E-B3FD-94106697EF27)
-8055-p.jpg?v=A3E861DA-3E0D-4C33-B95B-1F389DDBD092)
-8055-p.jpg?v=F9C7F7C1-EC5E-4155-8B45-BF9A0160DC36)
