20 FIELD GEOLOGY. 



it crosses the road between the sand-pit and where clay 

 was observed in the ditch. Beyond the road this feature 

 becomes less distinct, but we draw the line as a contour 

 from the shape of the ground, of course it sweeps round 

 to the right up the other valley, and just where it crosses 

 the footpath there is a pond. Here we can get no 

 direct evidence, but may fairly assume that thus far our 

 line is correct, for the pond would be about on the 

 junction dug through the sand which yields water into 

 the clay by which that water is upheld. Continuing 

 the contour it takes us across the road, which offers no 

 evidence other than a slight change in inclination, and 

 on to the lane beyond ; here, by picking in the banks T 

 we get sand in one place, clay in another just below, 

 and between the two runs the line of boundary. 



So far this is satisfactory, and we return to follow the 

 chalk line, the commencement of which was afforded by 

 the sand-pit near the church, but in passing up the 

 lane we find out by aid of the pick, and we mark on 

 the map, where it will be crossed by the chalk boundary. 

 From the sand-pit we draw a contour as before, getting 

 here and there in the ditches a little evidence to check 

 our work, round the point, across the footpath and the 

 main road, through the spot marked in the lane, and on 

 by the form of the ground. Here the line would seem to 

 turn back as it were upon itself, and to end where it 

 began, in the sand-pit ; it really does so, and the chalk 

 we have mapped thus is proved to be an " outlier." We 

 walk over the ground on the S. side of the brook, but 

 find no open sections, in all the ditches clay is visible 

 except at the extreme S.E. corner, where the soil is 

 very sandy. A well has been sunk at a spot which 



