Page 117 - Carbonate Facies in Geologic History

104 The Advent of Framebuilders in the Middle Paleozoic

CRATON

~

graptolite
facies ~ --
CRATON

• REEFS
E EVAPORITES
== SHELF FACIES
== SHellY FAUNA
:..=/::) GRAPTOLITE FACIES

100m-Thickneues in meters

Fig. IV-5. Middle Silurian facies of North America after Dott and Batten (1971, Fig. 11- 11)
showing peripheral distribution of mounds and reefs

V.Hede, V.Jux, and A.A.Manten) and the northern United States outcrops in
Illinois and Indiana (H.A.Lowenstam, E.R.Cummings and R.R.Shrock, A. V.Ca-
rozzi, D. A. Textoris, and J. 1. C. Ingels).
Regionally, the Gotland occurrence of small Silurian mounds lies along a
shallow shelf bordering the Baltic shield east of the Caledonian geosyncline. The
related Wenlock mounds of Britain (Colter, 1957; Scoffin, 1971) lie within the
geosyncline itself but presumably on a shallow platform near its border.
Silurian outcrops in North America are widely distributed though scattered
across the craton and it is possible to obtain a clearer picture of the regional
setting than in Europe. Silurian strata were extensively removed by erosion dur-