168 
THE AVONIAN OF THE AVON GORGE 
Plate X. Observatory Hill and the Great Fault. 
The plane of overthrust is seen, separating sharply the massive 83 
beds above from the contorted D2 series below. 
Plate XI. The Southern end of Clifton Down ; Observatory Hill and 
the Suspension Bridge. 
The Upper Dihuno'ph'^lum-Tione (02)“ of the main section is seen to 
the left, sharply separated from the Upper Seminula-Tione (S2) of 
Observatory Hill by the Great Fault. 
At the right of the plate, the massive base of the Lower Dibunophyllum- 
zone is indistinctly seen, along the side of the upper part of the Old 
Zig-zag Path. 
Plates XII, to XV. illustrate the section on the Leigh Woods side ; they 
are arranged in descending order of the strata, from South to North. 
Plate XII. The ‘ Point ’ and Quarry 5. 
The slope above the tunnel is 'mainly composed of the ‘ Concretionary 
Beds ’ (uppermost S2), capped by the massive basal beds of the 
Lower Dibunophylluni-zone (D^). 
Quarry 5 exhibits the upper part of the Upper Seminula-Zione (S2). 
Plate XIII. Quarry 5 and Quarry 4. 
The Seminula-zone (S). 
In Quarry 4 (to the right), the ‘ Seminula- oolite ’ (lower S2) rests upon 
the upper part of the Lower Setninula-zone (S^). 
Plate XIV. Quarry 3 and part of Quarry 2. 
In Quarry 3 (to the left), the massive Caninia- oolite (C^) is capped 
by Caninia-shaleB (C2) and is underlain by the Z«wmosu-dolomites 
(Cl). 
Plate XV. Quarry 2 and Quarry 1. 
In Quarry 2 (to the left), a capping of Zammosa- dolomites (base of Ci) 
rests upon the Upper Zaphrentis-zone (7 and Z2). 
In Quarry 1 (to the right), all the beds included in the plate belong 
to the Lower, ZapTirentis-zone (Zi). Lower beds (/3 and K2) are 
hoAvever exposed at the base of the Quarry, immediately north of 
the beds represented in the plate. 
Plate XVI. Sketch Map of the Avon Gorge ; accompanied by Horizontal 
and Vertical Sections, illustrating the Lithological and Zonal 
succession. [Reproduced from Quart. Joiirn. Geol. 80c., vol. 61, 
PI. 27 ,by kind permission of the Council of the Geological Society.] 
