The Jackson formation south-west of the Lisbon beds, is made up chiefly of grey calcareous clay marls, bluish lignitic clays, green-sand and grey siliceous sands.
It occurs in such abundance in certain geological formations as to give rise to the name of green-sand.
Wanting Danian Upper Chalk Senonian Middle Chalk Turonian Lower Chalk Cenomanian Upper Green-sand Gault Albian Aptian Lower Green-sand Valenginian Urgonian Wealden Neocomian In the continental classification the deposits from the Gault downwards are grouped as Lower Cretaceous; but in Great Britain there is a strong break below the Gault and 'none above; and the Gault is therefore classed as Upper Cretaceous.
The Green Sand Beach in the south of the island of Hawaii (Big Island) contains just this green, well-rounded olivine.
