51 



a little to the south of Ascog mill, as shown in the annexed section 

 giving the various beds : 



(s) Sandstone; (f) terrace and road; (jf) greenstone; (a) trap-tuff; (5) red ochre; 

 (c) lignite bed; (c?) pisolitic ochre; (e) porphyritic amygdaloid, the upper portion 

 much altered. 



The lowest bed resting on the sandstone is a small-grained rudely 

 columnar greenstone ; the junction is, however, concealed. Over 

 this is a trap-tuff with a base of greenstone, and imbedded spherical 

 lumps of the same substance. This is followed by a bed of red ochre 

 of coarse texture, traversed by numerous black iron-seams, which 

 have doubtless been produced from a change in the oxidation of the 

 component iron. Over this is the lignite bed : it is three feet thick, 

 and consists of hard stony coal, interstratified with a yellowish-white 

 shale, both being much intermixed with pyrites. The coal has been 

 so much altered throughout its whole thickness by the contact of the 

 trap rock, that Mr. Rose of Edinburgh, to whose examination the 

 best specimens that could be selected were submitted, in order 

 that he might determine the species of wood, but without any note 

 of the geological situation of the coal, was " unable to obtain a slice 

 in consequence of the structure being altered by the contact of a whin 

 dike." The coal has been worked to some extent by driving an 

 adit inwards on the line of the dip, which is about 20 to the 

 westward ; but the workings have been for some time abandoned, 

 and the inner and lower portions are now full of water. 



The floor of the coal has been already described. The roof is a 

 peculiar rock. It consists of a base or paste of an ochreous steatite, 

 with imbedded round pieces of the same substance, and may hence 

 be called a pisolitic ochre ; it is three and a-half yards thick. The 

 bed above this ' L is of the same character ; but the base feels less 

 unctuous, and with the imbedded steatite it contains also imbedded 

 calcareous spar. The base effervesces briskly with an acid; and 



