28 Tlie American Geologise. Januar.v, i897 
distinguishes them from the knvor and next hitj-her strata nearly pvery- 
where. 
\. Stictopora HKI). 
At Saint Paul, Minnesota, this V)ed is found thirty feet thick and con- 
sists of green clay, with a few thin strata of limeptone that is made up 
of fossils. It is marked oflf from the bed below it by the contrasted 
purity of the clay and by the abpeuce of certain species of fossils. The 
top is separated from the next bed along the undulating upper surface 
of a stratum of limestone. 
The Stictopora bed is seldom well exposed in Minnesota, but is known 
to exist in Goodhue. Olmsted and Fillmore countiep, like at SainfPanl, 
but with fewer limestone strata. At Decorah, Iowa, it is exposed on 
the north side of the river, 15 feet, and is probably 50 feet or more thick, 
but contains no limestone and scarcely any fossils. At Lancaster, Wis., 
shale at the base gradates to limestone with marl laminae in the upper 
part of the bed. Farther east and south in Wisconsin, carbonaceous or 
crystalline limestone with brachiopod shells preserved, as at Platteville, 
or heavily bedded dolomitic limestone, as at Dodge ville, or limestone in 
irregulai- strata, with shaley lamina, as at Beloit, are local alterations 
.of the limestone strata that there form this bed. 
The thickness of the "Upper Buff" bed at Beloit, Wis., has been es- 
timated at 55 feet,* but is probably much less. The estimate is diflBcult 
to verify. The thickness is as follows: Saint Paul, 30 feet; Fillmore 
Co., Minn., 25 feet or more; Decorah, Iowa, 20 feet or more; Dodgeville, 
Wis., 30 feet; Beloit, 35 feet; Rockton, Ills., 35 feet. 
The name Stictopora bed was given by me from SiicUypora viuiabiliH 
Ulr. Mr. Ulrich has since then changed the generic name to Rldni- 
dictya'f and has recognized the bed under the changed name, "Rhini- 
dictya bed,"{ an unnecessary correction. 
5. Fcrcoir) bed. 
At St. Paul, Minn., the Fucoid bed is 18 feet thick and consists of 
fossiliferous shaley clay. Twiglike fucoids or sponges are numerous 
even at the base and make up more of each successive stratum until 
at the top of the bed a solid mass of them obtains. A few thin strata 
of fine-grained, heavy limestone are intercalated, and near the top are 
laminae with oolitic limonite. The latter occurs as deep as to the base 
of the bed in northwestern Wisconsin. It is found southward as far as 
Fillmore county, Minnesota. 
The shaley clay full of 'fucoids' at Saint Paul, becomes more and 
more calcareous and the fucoids fewer towards the south and south- 
east. In Goodhue county it is very fossiliferous but is not well ex- 
posed. The same is true in Olmsted and Fillmore counties, where this 
bed seems to be thinner, although of that one is not certain because 
the line of springs is along its top and local stratigraphic changes are 
probable in all known exposures. At Decorah, Iowa, it shows alter- 
*T. C. Chamberlin, Geology of Wisconsin, vol. ii, p. 295 and 297. 
tVol. Ill, Final rep. Geol. Nat. Hist. Survev of Minnesota, p. 125. 
JExtr. 19th Ann. rep. Geol. Nat. Hist. Survey of Minnesota, p. 212. 
