"There was no frigid zone, and there may have been no excessively torrid zone."
While of the Silurian coral limestones of the Arctic regions he says:
"The formation of thick strata of limestone shows that life like that of the lower latitudes not only existed there, but flourished in profusion."[69]
Howorth thus quotes Colonel Fielden, the Arctic explorer, regarding the fossil Sclerodermic corals of the Silurian, widely distributed in the Arctic regions:
"These undoubted reef-forming corals of the Silurian epoch were just as much inhabitants of warm water in northern latitudes at that period as are the Sclerodermata of to-day in the Indo-Pacific and Atlantic oceans.... These corals were forms of life which must have been tropical in habits and requirement."
In fact coral limestones of the Carboniferous system are the nearest known fossiliferous rocks to the North Pole, and from the strike of the beds must underlie the Polar Sea. In the words of Howorth, "Coal strata with similar fossils have occurred all round the Polar basin ... and may be said, therefore, to have occupied a continuous cap around the North Pole."[70]
Again I quote from Howorth regarding the Mesozoic rocks:
"This very widespread fauna and flora proves that the high temperature of the Secondary era prevailed in all latitudes, and not only so, it pervaded them apparently continuously without a break. There is no evidence whatever, known to me, that can be derived from the fauna and flora of Secondary times, which points to any period of cold as even possible. There are no shrunken and stunted forms, and no types such as we associate with cold conditions, and no changes evidenced by intercalated beds showing vicissitudes of life."
The following is from Nordenskiold, as quoted by Howorth, and refers to the whole geological series: