41 



geologist to work, and falls short of few places in many interesting 

 particulars, as I shall attempt to show in the sequel. 



Mr. Hull declares that of all the formations in this district, there is 

 none which affords fewer opportunities of examination than the Upper 

 Lias shale. Its surface indications are useless, and further, they are too 

 often concealed altogether by the debris, from its crumbling nature. My 

 observation confirms this : the wind, frost, and rain, of the last winter 

 have nearly buried the lower beds of our hill with tumbled shingly rubble. 

 The quarries on the top of Churchdown Hill are two, which may be 

 distinguished as the North and the South. The South Quarry being the 

 larger and yielding the better section. The upper set of strata there 

 disclosed constitutes the Communis zone, and, as the name Communis, now 

 generally used for this zone, cannot, as yet, be declared thoroughly 

 naturalized, it may not be amiss to prefix the chief synonyms, as 

 employed by some of the leading writers on the subject. 

 Stnontms and Equivalents. — The Communis beds are : 

 The Upper Lias Shale (lower part), . . Phillips 



The Alum Shale (lower part), Toung Sf Bird 



The Upper Lias (lower part), Murchison 



The Communis Zone (lower part), .... WrigM 

 Etage Toargien (partie inferieure) .... d' Orligny 



Bituminose Mergelschiefer ScMoiheim 



Posidonia Schiefer Bronn 



Schiste et Marne de Grand Cour .... Chapuis et Dewalque 



Schistes de Boll Marcou 



Posdionomya Schiefer et Monotis Kalk Homer 



Lias (epsUon) Quenstedt 



Liasschiefer Von Buck 



Posidonomya bett Oppel 



And under part of the Upper Lias of English, French, and German 

 geologists. 



The two Churchdown quarries lie relatively to each other, nearly in the 

 line of their dip, namely north and south, with a gentle elevation of their 

 beds to the south, at an angle of 8° or 10°. At this small inclination, a 

 right line of prolongation, directed to Paiuswick HiQ (altitude 929'), 

 would exactly coincide with the same strata, at an equal value of the 

 angle : these very beds attaining at Painswick the thickness of 80', while 

 at Churchdown they are about 10'. Churchdown thus presents a 

 truncated summit, from its ancient capping being eroded to this extent, 

 and washed into the vale, where it is strewn in well-defined bands of 

 gravel, sand, and silt, belting the contour of the base, and then wending 

 their course over the plain. Were these surveyed and mapped they 



