THE AVONIAN OF THE AVON GORGE 
167 
EXPLANATION OF PLATES. 
Plates I. to XI. illustrate the section on the Clifton side of the Avon ; 
they are arranged in ascending order of the strata, from North to 
South. 
Plate I. The Northern end of the section, in the vicinity of ^ Cook’s 
Folly.’ 
To the left : Modiola- Phase (Km) capped by ‘ Bryozoa Bed.’ 
In the middle : the main Cleistopora-iione. (K^ and K2), poorly exposed. 
To the right : the Zaphrentis-ione, constituting the ‘ Black- Rock.’ 
Plate II. The two railway cuttings, north of ‘ Cook’s Folly.’ 
To the left : Jfot^mZa-shales (Km), capped by ‘ Bryozoa Bed ’ ; suc- 
ceeded, near the signal-post to the right of the plate, by the normal 
development of the Lower Cleistopora-zone (Kj^). 
Plate III. The Black-Rock Quarry and the North-slope of the Gully 
(Durdham Down). 
To the left (below the cave) : Lower Zaphrentis-zone (Z^). 
Main quarry : Upper Zaphrentis-zone (Zg and 7). 
Immediately below the Gully-slope: base of Syringothyris-zone (Ci, 
/ammosa-dolomites ). 
Plate IV. The gully and the ‘ Oolite Quarry ’ (North-end of Clifton 
Down). 
To the left (north slope of gully) : laminosa-dolomites (base of Cj)- 
To the right (‘ Oolite Quarry ’) : ^uwwosa-dolomites and Caninia- 
oolite, capped by Gawmia-shales (C^ capped ’by C2). 
Plate V. Gully to Great Quarry. 
To the left : Caninia- oolite (C^). 
In the middle : shales and Caninia-dolomites, (C2). 
To the right (north end of Great Quarry) : Lower Seminula-zone (S^). 
Plate Va. Railway cutting between the Oolite-Quarry and the Great 
Quarry. 
The Gawmf a- shales and Gun mm- dolomites (C2). 
Plate VI. The Northern end of the Great Quarry. 
Lower Seniinula-zone (S^). 
Plate VIT. The Great Quarry and the New Zig-zag. 
The Seminula-zone (S) capped, immediately below the north-slope 
of the New Zig-zag, by the basal beds of the Lower Dihunophyllum- 
zone (Dj). 
To the right : Exposure of D^ beds, south of the New Zig-zag. 
Plate VIII. The Northern part of Clifton Down, dissected by the de- 
pression of the New Zig-zag. 
(Bridge Valley Road is seen, encircling the southern slope of this 
depression, and to the right of the plate lie Point Villa and the 
entrance to the Hotwell Tunnel. 
The Seminula-zone (S) and the Lower Dihunophyllmn-zone (Dj). 
Plate IX. The lower portion of Bridge Valley Road" and the northern 
end of Observatory Hill. 
The Upper Dihunophyllum -zone is exposed along the sides of the 
Towing Path and of Bridge Valley Road. 
To the right : The massive VppeT-Seminula beds (83) of Observatory 
Hill are seen, faulted against contorted beds which belong to the 
Upper Dibunophyllum-zone (Dg). 
