Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/216

 visible grains of white or greenish-white felspar and hornblende, and often exhibits an arrangement in egg-shaped masses, from a foot to a yard in length, each mass being obscurely composed of thick curved concentric laminæ, and pretty uniformly covered externally by a coat, an inch or more in thickness, of hard fibrous calcareous spar. In this variety, where the greenstone is not figurate, it is more or less amygdaloidal, inclosing globules of radiated calcareous spar. Another remarkable variety that it assumes, is where, in addition to the two former component parts, there is a predominating proportion of flesh-coloured felspar giving the rock a sienitic appearance. All these varieties are strongly magnetical, but the figurate is most so.

At Little Wenlock this rock appears for the most part to occupy the space between the coal-formation and the subjacent limestone, and accordingly, at the eastern foot of the hill may be seen the great body of the coal at its usual angle, while the little-flint sandstone (the lowest member of the coal-formation) highly elevated; covers the ascent of the hill, and is found in several detached patches on its summit, but in nearly horizontal strata. The general cultivation of the surface of this hill is a great obstruction to minute research, a difficulty that fortunately does not apply to the other great deposit at Steeraway, where an excellent opportunity of observation is afforded by the limestone quarries at that place. If we begin our research in a little shallow valley, about two hundred yards wide, that lies at the bottom of the eastern side of the Steeraway-hill, we shall first find the flint-coal and the little-flint sandstone cropping out very evenly at an angle of about 6° on the eastern side of the valley. The bottom of the valley itself, as far as can be ascertained, on account of the covering of grass which overspreads its surface, is die-earth. The western side of the valley (the