204 Dr. Bright on the Strata 



rhomb, sometimes that of the dog's-tooth, and sometimes very com- 

 plicated figures with numerous truncations. The whole cavity of 

 the nodule is generally lined with small crystals, which are highly 

 phosphorescent when thrown on an iron plate heated almost to 

 redness. 



On cutting through the loam there is generally found a bed of 

 ochreous iron-stone about \\ foot thick. It is not known to what 

 distance this bed of loam extends. The nodules have as yet been 

 found chiefly in Hung-road wood, and some varying a little in ap- 

 pearance are seen on the opposite side of the river. 



To the west of Crokerne Pill you find only a low alluvial plain, 

 scarcely raised above high-water mark, and this continues on both 

 sides of the Avon until it falls into the Severn. 



With regard to the springs in the district I have been describing, 

 it may be observed that those in the limestone are low and situated 

 in the ravines, breaking out in many cases between high and low 

 water mark. The hot spring at the Wells rises in the limestone 26 

 feet below high water mark, and 10 feet above low water, and no 

 water is found at Clifton until the wells are sunk nearly to that 

 depth. When you come to the sand-ridge upon which Leigh is 

 situated, the springs are always found to rise in a high level, and 

 they afford a good supply of water. In the horizontal strata to the 

 west of Leigh very good water is obtained by sinking to the second 

 or thick bed of breccia, or at the utmost by sinking a few feet into 

 the stratum. There is a little spring in Hung-road wood which 

 though perfectly clear has the property of covering every thing over 

 which it flows with a brown calcareous crust. The quantity of 

 water is small, and in summer the stream is frequently dried up. 



As to the nature of the soil, the valley of Bristol and Ashton is as 

 verdant an extent of pasture land as any in the kingdom. Its rich 



