98 The Rev. W. Buckland on the Excavation of Valleys, Ssc 



identical beds ; and the commencements of them all originate within the area 

 and on the south side of the escarpment of the green sand. 



The valley of the Sid, as it is coloured in the annexed map, may from its 

 shortness and simplicity be taken as an example of the rest ; it originates in 

 the green sand, but soon cuts down to the red marl, and continues upon it to 

 the sea ; in both these respects it agrees with the upper branches of the 

 Otter, and with the valleys that fall from the west into that of the Axe. 



But in those cases where the lias and oolite formations are interposed 

 between the red marl and green sand, the base of the valley varies with the 

 variation of the substratum ; as will appear on comparing the opposite sides of 

 the lower valleys of the Otter, the Axe, and the Char, with the variations of 

 their substrata, as expressed in the map. 



The valley of Lyme is of equal simplicity with that of Sidmouth, and differs 

 only in that its lower strata are composed of lias instead of red marl : but the 

 valleys of Chideock, Bridport, and Burton, being within the area of the oolite 

 formation, have their lower slopes composed of oolite subjacent to the green 

 sand; whilst that of Charmouth is of a mixed nature, having its western 

 branches in green sand reposing on lias, and in some of its eastern ramifica- 

 tions intersecting also the oolite. In the same manner, the valley of the Axe 

 has lias inteiposed between the green sand and red marl on its east flank, but 

 none at all on its western side, below the town of Axminster. These apparent 

 anomalies form no exception to the general principle, that the variation of the 

 sides of the valleys is always consistent with that which is simply referable to 

 the variation of the substrata, on which the denuding waters had to exert 

 their force. It is moreover such as can be explained on no other theory than 

 that of the strata having at one time been connected continuously across the 

 now void spaces which constitute the valleys. 



The following section, taken from a series of lias quarries on the two oppo- 

 site sides of the valley of the Axe near Axminster, will show the degree of mi- 

 nuteness to which this correspondence extends : 



1. White lias... Slaty andfissile, is used for flooring when split Ft. In. 



into slabs from two to three inches thick . . 2 

 Clay. 



2. Burrs Rough blue building stone 10 



Clay. 



3. Cockles. I . . . Flat and broad blue stone, containing shells 



and divided into two beds, each three 

 inches thick, with a parting of clay; is 

 used for building.— Total 10 



