320 Mr. Weaver's Geological Observations on 



vicinity of Tortvvorth^ the old red sandstone, carboniferous limestone, and 

 coal formation ; the second (or gypseous and saliferous series) includes the 

 calcareous conglomerate, magnesian limestone, and new red sandstone ; of 

 the third series, which comprises the lias and oolite limestones, the iron and 

 green sandstone, and the chalk, the lias and oolite limestones only appear 

 within this tract : and the fourth and last series, or the formations later than 

 the chalk, are also wanting. The first, or carboniferous series, reposes upon 

 a transition base, while the succeeding formations overlie, unconformably, both 

 the carboniferous group and the transition tract ; and this either continuously 

 or in dismembered portions. 



§ 5. In the parallel of Wickwar, (Section No. 3.), the elevated ridge of the 

 old red sandstone and its accompanying limestone, the strata of which dip 

 here toward the west, supports, high up on its eastern flank, a deposition of 

 calcareo-magnesian conglomerate, that upholds red clay marl (of the new red 

 sandstone formation) sustaining lias ; which last extends to the foot of the 

 oolite escarpment, beyond Ingatestone Common, on the east, a distance of near 

 three miles : — all these beds being arranged in a nearly horizontal position, 

 and forming stages more or less in the form of table lands, with a dip of 2° 

 or 3° towards the east. This part of the course of the western branch of the 

 Avon, is wrought out of the new red clay marl, and the subjacent calcareo- 

 magnesian conglomerate ; but in descending to the north, the valley expands 



composition evidently and principally resulting from mechanical agency. I do not however see any 

 material objection to the adoption of the term sedimentary^ as a substitute for Jlcetz; and hence 

 I shall employ it throughout the rcmainderof this paper. 



That sedimentary deposits occur in transition and primary tracts also, can be no valid objec- 

 tion to the use of the word in this more large and characteristic sense ; for these deposits consti- 

 tute in such cases merely partial and local sub-formations. In the same manner the term old 

 red sandstone is not incorrectly applied to the first member of the carboniferous series, although 

 red sandstone occurs also in transition tracts, and, it is affirmed, even in the primary; the latter 

 cases being only exceptions to a general and opposite rule, namely, that a crystalline structure is 

 the more prevalent characteristic ; while the red sandstone appears as a consistent and predomi- 

 nant formation, for the first time, and is therefore in a geological sense the oldest, in the first 

 great sedimentary or carboniferous period. 



An extended developement of this portion of the text (originally designed as an appendix to the 

 present paper) may be found in the Annals of Philosophy for Oct. Nov. and Dec. 1821 ; in 

 which I have taken a general, and in part also a detailed view of the flcetz formations, distributed in 

 four principal series ; the British members being there also compared with their equivalents on 

 the continent. See likewise on the same subject the Geological Remarks of the author in the 

 Annals of Philosophy, for August 1822 and May 1823. 



