86 FIELD GEOLOGY. 



heights were taken by aneroid, level, or theodolite. The 

 N". and S. boundaries of ea;ch, so far as the outlier is 

 concerned, would be united by straight lines, or the act- 

 ual lines of division would perhaps be more accurately 

 represented by being slightly depressed in the centre. 

 Dotted lines across the valley between the outlier and 

 the main mass, passing through the points of boundary, 

 will give the inclination at which they commence to dip 

 beneath the surface ; farther S. the chalk is shewn dip- 

 ping at an angle of 2 30'; the true dip is 3 but the sec- 

 tion line is oblique thereto, the deviation being 28, and 

 the apparent dip of 2 30' is found either by table or dia- 

 gram. The thickness of the Gault at the well being 

 known, 108 feet, the base of the deposit can be shewn 

 there and prolonged by dotted lines, as provisional only 

 until the section shall have been extended northwards 

 to the boundary of the formation. 



