MAPPING. 21 



we mark on the map, and is stated to be 110 feet in 

 depth. 



Note. Almost every bank where the road is in 

 cutting and every ditch of even moderate depth 

 will yield evidence of the kind required, when the 

 fallen soil and rubbish have been cleared away. 

 But in picking into a bank, in spudding at the side 

 of a ditch, or in cutting at the face of an exposed 

 section, care must be taken to get at the actual 

 stratum beneath the vegetable soil. In the absence 

 of ditches, trenches, and banks (and there are many 

 bleak spots bare of all such aids), we must pick or 

 bore through the surface soil here and there on 

 either side of the probable line of boundary, look 

 out for the heaps of stuff thrown out from their 

 holes by moles, rats, and rabbits these often afford 

 useful hints in an obscure area and last, but not 

 least, we must accustom our eye to judge from the 

 soil itself what is the rock which lies beneath, in 

 other words, from which it has been derived. 

 At home the lines should be permanently drawn with 

 Indian or other ink that will not run with wash of 

 colour; the brickyard, the sand-pit, and the section- 

 symbols inked in, and the pencil lines of bearing, &c., 

 erased ; the spaces between the lines may then be tinted 

 in any colours selected for the different formations. 



Let us now take in hand another slip, fig. 6. Here 

 -we start perhaps at the S.E. corner, which is on chalk, 

 for that rock is seen in a small pit at the back of the 

 farm, and the ditches by the roadside. The ground is 

 comparatively high here and overlooks a broad flat to 

 the 1ST. which is traversed by a fair-sized brook. In 



