How far down in the earth would you have to go before you reach the layer of rock that was on the surface during the

Question: How far down in the earth would you have to go before you reach the layer of rock that was on the surface during the Cambrian period
- Keywords:
  fossil,
  geology,
  palaeontology
Asked by next1tag on 13 Mar 2024.
- Andrew McDowall answered on 13 Mar 2024:
  
  It depends where in the world you are. If you’re in parts of north-west and west Wales Cambrian rocks are on the surface thanks to the lifting and tilting of the layers of rocks when the North American and European plates collided to form a massive range of mountains – the Caledonian Orogeny (“Scottish Mountain Building Phase”), the remains of which can now be found in Norway, Scotland, Greenland and the USA – . In Wales this resulted in what was sea floor being lifted and tilted so that what was horizontal is now, in places, vertical and forms hills and mountains.
  
  Geology was pioneered in the UK and the country has been extensively studied and mapped, which is why many of the terms and ages relate to the UK – Cambrian (Wales), Silurian (South Wales), Ordovician (North Wales), Devonian (Devon) etc. For a small island we’ve a remarkable range of geology.

Question: How far down in the earth would you have to go before you reach the layer of rock that was on the surface during the Cambrian period