544 Prof. 8S. H. Reynolds—The Rocks of the Avon Section. 
frequent and tubicolous annelids occur. The beds are of shallow- 
water character, and constitute the earliest Modiola phase of the 
Avon Section. 
The Bryozoa Bed (horizon a) consists of massive ferruginous 
limestone, mainly composed of crinoids, but with very plentiful 
bryozoa at certain levels. 
K,.— Consists of shale and mudstone alternating with thin- 
bedded limestone. The principal limestone builders are crinoids 
and brachiopods. Ostracods and bryozoa are sometimes plentiful. 
In the “ Palate Bed” at the base Elasmobranch teeth are 
abundant. 
K,.—Only the upper part of this horizon is well exposed, the 
rocks consisting of thin-bedded highly fossiliferous limestone 
alternating with shale. Crinoids and brachiopods are the principal 
limestone builders. Ostracods and bryozoa are plentiful at some 
levels. A little dolomitization has taken place in some of the 
highest beds. 
B. The Zaphrentis Beds. 
Horizon 8.—On the right bank this horizon consists of rather 
massive limestone with crinoids and brachiopods. On the left 
bank the rock is thinner-bedded. 
Z,—The lower beds are crinoidal and brachiopodal limestones 
overlain by thick-bedded dolomite, capped by a chert band. The 
upper beds are dark dolomitized crinoidai limestone (petit granite), 
with many fossils, especially brachiopods. 
Z, and horizon y.—Consists almost throughout of dark crinoidal 
limestone (petit granite). The matrix is almost everywhere com- 
pletely dolomitized, but where this has not taken place foraminifera 
and Calcisphaera become for the first time plentiful. The larger 
fossils, particularly the crinoids, resist dolomitization and are the 
chief limestone builders. Brachiopods are less and corals more 
common than in Z,. The “ Fish Beds” at the top of Z, contain 
numerous Elasmobranch teeth and spines. 
C. The Syringothyris Beds. 
C,. (a) The Laminosa Dolomite —Consists of crinoidal limestone 
almost completely replaced by dolomite. At the top is the sub- 
oolite bed with abundant Chonetes and Orthotetes. 
C,(b) The Caninia Oolite——This is a fine-grained white oolite, 
the grains often enclosing foraminifera. Otber fossils are scanty. 
C,. The Caninia Dolomite-—The lower beds are composed of 
grey and pale dolomite alternating with calcareous shale and 
mudstone occasionally algal. The dolomite was originally in the 
main oolitic or foraminiferal limestone. The upper beds are mainly 
china-stones with ostracods and calcareous alge. The Canina 
dolomite commences the second Modiola phase of the Avon 
Section. 
