On Metallic Minerals. 361 



is thickly disseminated through some of the limestones in 

 the middle of tl»e series, and also in larger crystalline 

 pieces among the lowermost strata, with sulphurctof zinc, 

 sulphate of strontian, and calcareous spar — the whole 

 forming rounded nodules in the limestone. These nodules, 

 often entirely composed of fine light blue radiated sulphate 

 of strontian, are sometimes as large as a child's head, and 

 when detached from the limestone, which they are very 

 easily, a very fair imitation of a trencher, or soup-plate is 

 observed. This limestone has the as(ject of being more 

 sileceous and alluminous than that lying above it ; and 

 differs from it also by possessing nothing of a crystalline 

 character,* which the other docs, for although in both 

 cases the structure is compact, in the former the fracture 

 is dull, while in the latter it is glimmering, arising from 

 the reflection of light from the polished surfaces of minute 

 laminae. 



The limestone formation I am describing, has a stratifi- 

 cation which is nearly horizontal, except where, by the 

 apparent upraising of the older rock beneath it, since it 

 was de[)osited, a partial uncontinuous dip of the strata is 

 occasioned. These strata are sometimes separated by thia 

 iteanis of shale.f 



* Alilio(i(;h not cnvtalline, some of this limestone, as it lies on the shore, 

 in oemrly liurizuntal ttrata, resembles basalt in I'urm exceedingly. Mr. 

 Finch, ol"New ^oik, now lecturing at Montreal, was particularly" struck 

 with lU'u feature in the limestone. 



t The lime^lone of KinKklon, the groundwork of the forcpolng description, 

 it characteiized in -onu- pliices b_\ a rcMiaikablo c lu-rilio' ar_\ Mrmtiire, 

 which niBV be I luu described :- ovate, or rounded portions ot'lhe limestone 

 ■re M-paraled I'runi the m.i'iu body, by thin iiaillnvs I'.shnle, tli" \vaiideiin(,s 

 ofthe edgri of wliiih shale upon the surface ol* the limeiiti.ne, han been 

 aptly compared by Or. lii|{sby, to the ^uture» of the human skull. Tiiesc 

 c«ucreiiuiis are eatily teparuted from the main mass, and exhibit the shale 

 ICDcraUy lurroundinK them ou all »ides except tl.« uppcrniusl. This shala 



