50 THE TRAP FORMATION OF 



It is a hilly tract throughout ; but it may be better understood if it 

 be said, that at Sdgar, in its neighbourhood for eight or ten miles around, 

 and also in every part south of Sdgar, within the prescribed limits, and 

 as far west as Hasanahad, may be seen ranges of low hills extremely 

 clustered, though always detached, bending about in their short course 

 towards all points of the compass, and thus forming valleys of every con- 

 ceivable form, though not commonly of any great extent, and never dif- 

 ficult of access. But if the view be extended beyond the neighbourhood 

 of Sdgar, towards the east, or the west, or the north, expanded valleys will 

 gradually meet the eye, whilst the hills recede from it sinking in the hori- 

 zon as they surround valleys farther removed from Sdgar, until these 

 valleys are enlarged into extensive undulating plains, studded over with 

 isolated trap hills, occasionally of a conical, commonly of no determinate 

 form, whilst ever and anon, a short range of the same, deviating little from 

 a straight line, will have its beginning, and its ending, within view. 



These valleys and these extended open plains, are every where com- 

 posed, near the surface at least, of a trappean or basaltic mould, blackish 

 in color, which reposes either on a bed of basalt, or on a bed of compact 

 wacken. This compact basalt, or compact wacken, is either of an uniform 

 ovate form, or else it is in angular pieces of middling size, and underneath 

 these, as their occurrence may respectively be, lies an amygdaloid decom- 

 posing and decomposed, and which, as a retentive clay, keeps up the 

 water near the surface, and it is so met with throughout this tract. 



As to the trap hills, there is no occurrence of a bold bluff escarpment 

 belonging to them, their sides and ends are always sloping and rounded, 

 and, as far as the angle subtended from the summit is concerned, of easy 

 ascent. Their surfaces are thickly strewed over with masses of basalt 

 or wacken, imbedded in a basaltic or wacke clay, and differing only in size 



and 



