STRATA EXPOSED IN CONSTRUCTING FILTON-AVONMOUTH RAILWAY. 13 
vide diagram page 17. The Pecten beds 14 and 16 are above 
the shales in which Avicula contorta is usually most abundant ; 
bed 18 is below these shales, and the Pectens in it, although common 
enough, are generally of small size. 
The hard shale (19) is discussed in Section V. 
The bone bed group (21) exhibits considerable lateral variability. 
Speaking generally it passes from a series of thin stratified beds in 
the eastern cutting, to a definite breccia at the end of the western 
cutting. At an intermediate point, viz., just West of the tunnel, 
the sequence is as follows : — 
Bed 20, 5 inches. 
Shale ... ... ... 1 inch. 
Bone bed, ^ — 2 inches 
Shale 
Bone bed, 1 — 3 inches 
500 yards further West the character of the bone bed series is 
markedly different. 
Bed 20, 5 inches. 
H.,. 
2 inches. 
'Sandy bed, very irony ... ... 3 inches. 
2 or 3 pyritic grits with fibrous calcite 
partings and containing Schizodus 2 ,, 
Calcareous breccia, resembling the bone 
bed at Aust. Some of the included 
fragments full of Schizodus^ 3 
— 8 inches ... ... ... 5 inches. 
Irony sand ... .. ... 2 ,, 
A little further West a band of dark blue limestone, consisting 
almost entirely of shells of Schizodus was found above the bone bed ; 
but usually this bed is broken up and its fragments intermixed with 
the bone bed breccia. 
At the present time the infra bone bed series can be seen only 
in the western cutting. The nodular band of brecciated limestone 
(23) is the only hard bed in this series. It makes a prominent and 
regular feature, maintaining its position in relation to the bone bed 
above and the tea-green marls beneath, to the end of the section. 
This rock is quite unfossiliferous ; its appearance suggests the con- 
temporaneous breaking up of a hardened mud. 
The shales (24) are poor in fossils ; scales and teeth occur occasion- 
ally, and on certain levels, chiefly about four feet from the base, 
isolated specimens of Avicula contorta, Schizodus Ewaldi, and 
Protocardium sp., were collected. Generally these shales rest directly 
on a nodular band of hard grey marl, the line of junction being 
quite sharp ; occasionally, however, a thin sandy seam intervenes 
between the black shales of the Rhsetic and the tea-green marl of 
the Keuper series. 
In a subordinate cutting a little West of this section only the 
red marls of the Keuper series are seen. In them is a small fault with 
a downthrow to the West of about six feet. This is the only fault 
observed throughout the sections. 
