Marsh, who, after 1870, discovered a great number of bird remains in the Cretaceous strata of North America.
In the lower strata were discovered the remnants of Cyclopean or prehistoric architecture already mentioned.
Its congeners even then lived in England, as is proved by the fact that their relics have been found in the Stonesfield oolitic rocks, the deposition of which is separated from that which gave rise to the Paris Tertiary strata by an abyss of past time which we cannot venture to express even in thousands of years.
The mountains are composed in great part of Paleozoic strata, often modified by vulcanism and greatly denuded and sculptured by wind and water erosion.
The successive " Minoan " strata, which go well back into the fourth millennium B.C., reach down to a depth of about 17 ft.