GEOGNOSY OF EAST LOTHIAN. 227 



No fixed primitive rocks have hitherto been dis- 

 covered in this part of Scotland. The oldest of the 

 fixed rocks are those of the transition class, of which 

 the following species have been observed ; granite, 

 syenite, porphyry, greenstone, clay-slate, grey- 

 wacke, and flinty-slate. 



These transition rocks having been already de- 

 scribed by a member of our Society, it will not be 

 necessary to enter into any further details in regard 

 to them. We shall, now, therefore, proceed to give 

 an account of the Secondary rocks. 



1. — Red Sandstone. 



The first of these is Red Sandstone. This rock 

 forms a considerable portion of the county ; and^ 

 where its junctions can be observed, it is found 

 to rest on transition rocks, and to be covered with 

 the coal formation. Its most frequent colours are 

 red, inclining to brown ; and sometimes it is yel- 

 lowish or greyish white. Its principal ingredient 

 is quartz, which is in grains ; and these are either 

 joined together, without a basis or ground, or they 

 are imbedded in a red-coloured clay. It alternates 

 from very fine to very coarse granular, thus passing 

 into conglomerate. It is distinctly stratified, and 

 the strata vary from a few inches to several yards 

 in thickness. The strata are either horizontal or in- 

 clined ; but the angle of inclination seldom exceeds 

 45°. The general direction is from N. E. to S. W., 

 but the dip varies. It contains, as subordinate beds, 



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