51�Թ�

The fossils are therefore from the Upper Carboniferous or Pennsylvanian period, which is often called the “Coal Age,” since much of the world’s coal originates from deposits of organic material laid down during that time.

Everywhere the chief folding seems to have occurred before the deposition of the highest beds of the Upper Carboniferous, which lie unconformably upon the folded older beds.

From the Upper Carboniferous onward, however, no marine deposits are known; and, as in Siberia, plant bearing beds are met with.

Several hollows and pipes in the carboniferous limestone about Orme’s Head contain clays and sands of mixed origin, including Upper Carboniferous, Triassic and drift materials.

The folded series, culminating originally in Upper Carboniferous strata, was worn down, perhaps as far back as Permian times, until it possessed a fairly uniform surface.