GIBB — OYSTER CONGLOMERATE BED AT BROMLEY. 327 
the oyster-conglomerate, mixed with rolled flints of various sizes, from 
that of a pea to a potato, varying in thickness from three to fourteen 
inches, upon which succeed thin layers of sand and pebbles for three 
feet, and lastly, the gravel, which varies from two to twelve and 
eighteen feet in depth. These are better represented in the following 
table : — 
Ft. In. 
1 Gravel two to twelve feet and 18 0 
2 Layers of sand and pebbles 3 0 
3 Oyster-conglomerate, mixed with small and large rolled 
flints, varying from three inches to 0 14 
4 Light brown and variegated sands, with a few pebbles and 
a few shells, thinning out two inches to 0 3 
6 Brown sand and pebbles, free from shells in layers, also 
dying out 0 14 
6 Variegated brown sand, with a few pebbles three 
feet to 4 0 
7 Very light brown sand, with small pebbles and shells ... . 0 16 
8 Light brown sand with fragments of small shells 0 12 
9 Light grey uniform sand, averaging 12 0 
In that part of the excavation, situated towards the north, and which 
is at the same time the most elevated, the surface is a mixture of drift, 
sand, and chalk-detritus, overlying layers of sand and plastic clay form- 
ing the conglomerate. The depth of this drift may be from six to eight 
feet, and corresponds with the beds 1 and 2 in the foregoing table. 
Then for twenty-five feet are seen layers of sand and pebbles alternating 
with the oyster conglomerate rock, in which multitudes of shells are 
found forming a hard sort of breccia, which varies in thickness from six 
to eighteen inches ; and, in some places, consisting wholly of pretty 
large or of small rolled flints, and in others wholly of masses of oysters ; 
in others, again, of myriads of small shells, some in fragments, and 
others quite perfect, but very friable. In some of the layers, the con- 
glomerate has assumed the characters of a distinct sandstone, and is 
extremely hard; and when it consists of small pebbles, forms a 
pudding-stone. To these succeed the layers marked 4 to 9 in the 
table, but they were not completely exposed in the northern part of the 
excavation. The annexed diagram gives a section of this place. 
