874r Tke AuKiVican Gcofixjisf. December, KS'JT 
ments of Lingula shells are abundant, (jross- bedding char- 
acterizes this bed at Franconia. Fossils other than Lingula 
are not abundant within this formation. The conglomerates, 
however, that belong to this part of the Basal Sandstone series 
carry Obolella poUta Hall, and Linijulepis plniueformis Owen, 
besides other fragments not identified. Dresbach (a). 
The third subdivision of the series is oVjservable only 
above the Dalles, at Taylor's Falls, and at St. Croix Falls, in 
numerous exposures adjacent to the river channel. About 50 
feet of this stratum is exposed, and the lower limit is always 
within reasonable estimate, since it occupies the comparatively 
shallow basin through which the river flows. This-formation 
consists of sandy shales at several places; loose clayey shales 
extending farther up the river; calcareous shales in which 
thin layers of limestone one to three inches thick occur; and 
pyritiferous shales in which secondary iron sulphide in little 
pellets and grains make up almost one-third of the mass. 
Among these beds fossils are most abundant in the calcareous 
shales. The fauna is meagre in variety of species, but the 
number of individuals is unlimited. The species always ob- 
tainable is Lingulepis pinnoiformis Owen. The pyritiferous 
shales also carry a few fossil species, the pyrite serving as 
the fossilizing agent, while other beds of the formation carry 
almost no fossil forms. Dresbach (b). 
For these last two subdivisions as now limited the name 
Dresbach* of former writers is adopted. Dresbach, Minn., is 
the type locality where the succession was described by N. 
H. Winchell. Further proof of the correctness of the present 
correlation will be undertaken in the chapter on paleontology. 
The Conglomerates. The diabase conglomerates of the 
Cambrian age, lying alongside some of tlie igneous clitfs and 
ridges, are both the most interesting of the local phases and 
at the same time the most responsive to investigation. Among 
the localities of most ready access are the following: 
1st. At the water's edge, along the river, S. E. X^, N. W. 1^4, Sec. 15, 
T. 33 N., R. 19 W., where the conglomerate stands as a cliff 50 feet high 
with no visible ledge accompanying it at either side; 2d. On Mill street,, 
in the village of Taylor's Fails, at the railway crossing, and at the Vjrow 
*Geol. and Nat. Hist. Survey of Minn., Final Rep., vol.11, 1888, p. 
xxii. 
Bull. Geol. Soc. of America, vol. 6, 1895, p. 170. 
