204 Mr. AiKiN on the Wrek'm and on the 



visible grains of white or greenisli-vvhite 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 laminas, and pretty uniformly covered exter- 

 nally by a coat, an inch or more in thickness, of hard fibrous calcare- 

 ous 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 ad- 

 dition to the two former component parts, there is a predom.inating 

 proportion of flesh-coloured felspar giving the rock a sienitic ap- 

 pearance. All these varieties are strongly magnelical, 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 bcdy of the coal at its usual angle, while the little-flint sand^- 

 stone (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 cultiva- 

 tion of the surface of this hill is a great obstruction to minute re- 

 search, a difficulty that fortunately does not apply to the other great 

 deposit at Steeraway, where an excellent opportunity of observa- 

 tion 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 over- 

 spreads its surface, is die-earth. The western side of the valley (the 



