248 Dr Hibbert on the Limestone of Burdiehouse, 



SECTION VII— THE LIMESTONE OF MARINE ORIGIN AT FOUNT AINWELL, 



NEAR LOANHEAD. 



The limestone of Fountain-well, which occupies a sort of mid- 

 dle place in the system, forms a portion of the continuous bed, 

 which may be traced, cropping out at various sites, in a line, ex- 

 tending from the neighbourhood of Joppa to Gilmerton, and 

 thence to Fountain-well ; a distance of three miles. It is in 

 general very impure, being much mixed with siliceous matter, 

 whence its great hardness, which, in the absence of whinstone or 

 trap, has caused it to be used for repairing the highways. At 

 Gilmerton some portion of it is so much mixed up with argil- 

 laceous matter as to pass into common shale. 



This limestone, in its impure state, is named Limestone Blaes. 

 But it contains fakes, or seams, of very pure limestone, which at 

 Gilmerton are wrought for the kiln to the thickness of 14 feet. 

 The bed at Fountain- well encloses three fakes, or seams, each 

 about two feet thick, or 6| feet conjointly. 



The whole of the limestone, whether pure or impure, is of a 

 blue, or bluish grey, colour. 



To farther distinctions I shall allude when I have to compare 

 this limestone with that of Burdiehouse. In the mean time, I 

 shall remark, that it contains marine remains, such as encrinites, 

 corallines, producti, &c, which are severally absent in the Bur- 

 diehouse limestone. 



At Fountain-well, the circumstance most worthy of remark at 

 present, is the further increase of dip which has taken place in 

 the tilted and upper beds of the system under examination. In 

 the inferior bed of Burdiehouse, the dip was 23° to 25° to the 

 south-east ; but in the much higher limestone of Fountain-well, 

 it has increased to 50° or 52° south-east. 



SECTION VIII— THE UPPER SERIES OF SANDSTONES, SHALES, AND RICH SEAMS 

 OF COAL, FORMING THE LOANHEAD COAL-MEASURES. 



I shall, lastly, describe the strata superjacent to the Fountain- 

 well limestone. 



