114 Mr Lyell on a Dike of Serpentine cutting through 



No limestone, with some partial and unimportant excep- 

 tions, * occurs to the south of the Grampians, on the east side 

 of Scotland, between the clay-slate and the coal. If, therefore, 

 the inferior micaceous red and grey sandstones, sometimes 

 slightly calcareous, with their associated strata and trap rocks, 

 are grouped with the old red sandstone, the latter formation 

 must be regarded as of immense thickness, and as occupying, 

 to the exclusion of the English transition limestone series, 

 the whole space between the clay-slate and the coal. I have 

 considered these observations necessary, lest the strata, with 

 which the serpentine is associated in Forfarshire, should be 

 considered more recent than those in which it has often been 

 found elsewhere. This, I believe, is not the case, though such 

 an idea would be conveyed to most geologists if the red sand- 

 stone in question were described as a member of the old red 

 sandstone formation. 



I now hasten to a particular description of the serpentine and 

 accompanying strata, of which the annexed ground plan was 

 sketched on the spot. See Plate V. The Carity, a small river 

 which descends from the micaceous shist district in the northern 

 part of Forfarshire, enters, soon after quitting the Grampians, 

 a deep defile, near the farm of West Balloch, in the parish of 



large districts may.be examined without the occurrence of a single fossil, yet, 

 in some few places, be has met with some in the red sandstone, correspond- 

 ing precisely with such as characterize the English transition limestone. 



* A thin vein of limestone, corresponding exactly to the cornstone of 

 the English geologists, is found in the old red sandstone of Strathmore, 

 extending in a direction N. E. and S. W. from near Stracathro to Careslon, 

 and again in the same line at Reedie, a few miles S. W. of Kirriemuir. 

 The cornstone of Forfarshire, like that in England, contains no organic re- 

 mains, and is in small quantity, though in consequence of the scarcity of 

 limestone, it has, in many places, been burnt for lime. The trap rocks 

 also, as is well known, contain occasionally much' calcareous matter. For 

 an account of the limestone of Clunie, see the First Article, No. I. 

 of this Journal, by Dr MacCulloch. There is also a stratum of 

 limestone at the Boddin, to the S. of Montrose, which has been long 

 worked, but is now nearly exhausted. Although I have carefully ex- 

 amined this, it may be premature to pronounce an opinion on its geolo- 

 gical relations, until it has been compared with some other strata of lime- 

 stone, occurring near Montrose, which may perhaps belong to the same 

 formation. I am, however, at present inclined to refer the limestone of 

 the Boddin to an era more recent than the coal. 



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