108 



CARBONIFEROUS LIMESTONE OF LILLE SHALL. 



lower parts were rooted in the shale (/), whilst the upper passed up through the 

 bedded limestone e into the mass of red concretions, or " grum," d. It appeared, 

 therefore, to be precisely in its original position, and conveyed the impression that it 

 had remained undisturbed beneath the sea, whilst fine red sand at one time, and mud 

 with calcareous matter at another, were deposited around it. Fig. # of the wood-cut 

 represents the large shell Productus hemisphmricus , and gives by comparison an idea of 

 the great size of the coral. 



The section continued, in descending order, consists of 



g. Splothers, red small concretionary limestone and shale, much resembling the " Grum." 



h. Bulls' Livers, concretions rather larger than the " Splothers." All these overlying beds were formerly worked for lime, 



but are now abandoned. 



i. Bed and black shale. 



j. Strong-bedded pinkish red sandstone, with a few pebbles of white quartz. Some of these contain lime in the cement, and 

 are therefore calcareous grits. 



k. Bed stone :: "] These constitute the solid subcrystalline mass which is now the chief mine, and which the 



I. Captainer workmen call the upper measures. They vary in colour from light cream-colour to grey and 



m. Flags V red, and contain nearly the same fossils as the overlying beds. They are all worked underground 



n. Strong stone in a thickness of about eight yards, separated only by very thin wayboards. The shafts upon 



o. Bottom or white stone. J the dip have not been sunk beneath the floor of the " white stone." 

 p. Strong-bedded pink and red sandstone, with white quartz pebbles. 



q. Lower or Grey-limestone. This rock, from ten to twelve yards thick, is only seen on the rise of the strata to the northern 

 end of Lilleshall Hill, where it crops out. Like the other measures it is so associated with red and green shale, in 

 parts micaceous, that in the old open works a casual observer might conceive that the beds belonged to the New or 

 Old Red Sandstone. On fracture, however, it proves to be a dull grey flat-bedded limestone with a purple tinge, gritty, 

 earthy, and impure. Though it did not appear to contain the Productus hemisphcericus of the upper beds, I found in 

 it some well-known corals of the other beds of limestone. 



This Lilleshall deposit has been described in some detail, because it differs es- 

 sentially in many of its mineral characters from any of the varieties of the carboni- 

 ferous limestone, described in the sequel. The organic remains, however, clearly 

 belong to this formation, and are completely distinct from any which occur in the 

 overlying or underlying systems. This is particularly marked in the above-named 

 corals, which I have the authority of Mr. Lonsdale for stating, are unlike the 

 corals of the Silurian System. On the edges of this coal-field, therefore, we are 

 presented with a beautiful illustration of the superior value of organic remains to 

 mineral characters in identifying the age of rocks ; for at Lilleshall the carboniferous 

 limestone consists of red and green, and light grey limestone, with abundance of red 

 concretions, in parts strongly resembling the " cornstones" of the New and Old Red 

 Sandstone ; whilst at Steeraway, only five miles distant, it is a black, dark grey, 

 thick-bedded rock, and void of all concretions. In the one case the associated sand- 



Derb., PI. 43. fig. 3 and 4 ; Stylina, Parkinson; Columnaria floriformis, De Blainville ; Astrcea mammillaris} 

 Fischer de Waldheim; Lithostrotion floriforme, Fleming; Cyathophyllum floriforme, Phillips. Mr. Lons- 

 dale is of opinion that this coral ought to retain the generic name of Lhwydd, which has been adopted by Dr, 

 Fleming. .... 



