92 



on two or three sides by lower ground ; and sometimes on the 

 inclines of the hills. 



Under the last-mentioned circumstances the said inclines are 

 either very gradual or in terraces. As long as the ground 

 remains in its pristine state, very few or no watercourse are 

 distinguishable ; those found are very wide, shallow, and carry 

 very little water. But as soon as the continuity of the turf, 

 noted for its luxuriance, is broken by the farmer's plough, the 

 traveller's dray, or an exceptionally heavy thunderstorm, the 

 bed rapidly deepens, on account of the peculiar nature of the 

 soil, and in a short time assumes respectable dimensions, 

 specially remarkable for the steepness of its banks. If not 

 carefully attended to, the denudation proceeds at so rapid a 

 rate that perhaps in less than a century the whole surface of 

 these regions would, for a considerable depth, be carried out 

 to sea. The cause of this lies in the constitution of the soil. 

 It consists of a dark-red or brown clay, containing much lime 

 and a little fine gravel. Soine portions are almost black, other 

 patches grey or bluish. The former occupy generally a part of 

 the elevation and inner slope, sometimes the lowest part also ; 

 the latter the remaining part of the slope, generally that facing 

 the higher level of the whole area. However, even where the 

 differences in colour are less marked, a newly-ploughed field of 

 virgin soil of this description presents, when viewed from some 

 distance, always a curious irregularly mottled appearance. 



When dry the whole surface is scored in every direction by 

 numerous cracks, often from one to two inches wide, and 

 extending to a considerable depth. The light-coloured patches 

 are much less affected than the darker, but all are rendered in 

 proportion more or less friable and yielding to a most fatiguing 

 extent for weary travellers, &c, and in a very short time the 

 feet of animals and the wheels of vehicles triturate it into 

 incredibly minute particles, forming clouds of dust. If a 

 heavy shower of rain fall for an ho\ir or two the whole surface 

 is changed into an exceedingly adhesive mire, heavily clogging 

 feet and wheels with tough pug. Owing to the uneven 

 surface the water is detained, and a large quantity at once 

 percolates through the larger and smaller cracks, carrying 

 with it a considerable moiety of the loose soil to some depth, 

 and widening the channel in the descent. In the narrower 

 portions of the latter, grass leaves, stray pebbles, &c, will be 

 arrested, and will prevent the closing of the fissure, when the 

 clay expands on saturation, and will facilitate its reopening 

 when the clay shrinks on drying. Actual repeated obser- 

 vations seem to demonstrate that at least the larger of these 

 fissures do open year after year, and are productive at 

 times of rather practical annoyances. Thus a large crack through 



