The author enumerated seven different deposits, overlying the rocks of the district, and subjacent to the existing soil which supports vegetation. These he described in the following order, beginning with the lowest.

(1.) Sand and fine gravel, which in some places form beds twelve feet thick.

(2.) Boulder-clay—being a stiff black or dark brown clay, characterised by enormous boulders imbedded in it, and which is occasionally forty feet thick.