CHAPTER XXV.

Lower Carboniferous or Gypsiferous Formation of Nova Scotia. Why formerly considered as newer than the productive Coal.-Determination of its true Age.—Sections near Windsor. - Supposed Reptilian Footsteps. Section on the Shubenacadie. Large Masses of Gypsum. Their Origin. Volcanic Action contemporaneous with Nova Scotia Coal Measures. Limestone with Marine Shells. - Table of Organic Remains of the Carboniferous Limestone of Nova Scotia and Island of Cape Breton.

THE productive coal-measures near Minudie, described in the last Chapter, may be regarded as the middle of the carboniferous series of Nova Scotia; while the strata above them, including the beds with Modiola, h, i, (fig. 19. p. 180.), and the sandstones and shales farther to the south, in the same region, together with a corresponding series near Pictou, and the lower sandstone of Prince Edward's Island, ascertained by Mr. Dawson to contain coal-plants, may be all classed as the Upper Carboniferous division, in which no seams of coal have yet been found. Lastly, we may regard an enormous mass of red and brown sandstones and red marls, the lower portions of which include beds of gypsum, and limestones charged with marine shells and corals, as the Lower Carboniferous or

gypsiferous series. In this division grits and shales, with some true coal plants and some thin seams of impure coal are occasionally met with.

Before my visit to Nova Scotia, the group last mentioned had been considered, chiefly, I believe, from its resemblance to the gypsiferous red marls above the coal in Europe, as the uppermost formation in Nova Scotia. Mr. Logan, in his first brief excursion in 1841 to the Windsor district, where the beds are greatly disturbed, had little more than time to collect some of the most abundant fossils; and these, when submitted to several able palæontologists, (to M. de Verneuil among others), were thought to confirm the opinion previously entertained, that the strata were newer than the coal. That geologists should at first have arrived at this result will surprise no one who is aware how many of the fossils of our Magnesian limestone and coal resemble each other, or who studies the list given at p. 218., in which several species both of shells and corals from Nova Scotia, identical or closely allied to well-known Permian or Magnesian limestone forms, are enumerated. By these considerations my friend Mr. Murchison was induced, in his Anniversary Address to the Geological Society of London, in 1843, to pronounce the gypsiferous rocks of Nova Scotia as the 'equivalents in age of the Permian group of Russia.

My first inspection of the country near Windsor, followed by an examination of the cliffs near Minudie, described in the last Chapter, led me to an opposite view, strengthened by discussions with Mr. Richard Brown of Sydney, and Mr. J. W. Dawson of Pictou, with whom I explored the cliffs of the East River, south of the Albion Mines, near Pictou. I then examined with care, in company with Messrs. Dawson and Duncan, the fine section laid open in the cliffs of the Shubenacadie, a river which intersects Nova Scotia from south to north, cutting through the gypsiferous strata for a distance of twenty miles. Lastly, I had an opportunity of studying at my leisure in London the fossils collected from various localities, and I had then no longer any hesitation in announcing to the Geological Society my conviction, that the gypsiferous strata were older than the productive coal-measures, whether of the South Joggins or of Pictou. I also stated at the same time my opinion that I considered them as constituting a lower member of the Carboniferous group, containing fossil plants of the coal, with shells and corals of the carboniferous limestone.

Mr. Richard Brown, after our meeting at the Albion Mines in 1842, kindly undertook, at my request, to make a re-examination of part of Cape