EN DEODUCHION TOly OL mi PART i: 
THE LOWER SILURIAN DEPOSITS OF THE UPPER MISSISSIPPI PROV- 
INCE: A CORRELATION OF THE STRATA WITH THOSE IN THE 
CINCINNATI, TENNESSEE, NEW YORK AND CANADIAN 
PROVINCES, AND THE STRATIGRAPHIC AND 
GEOGRAPHIC DISTRIBUTION OF THE 
FOSSILS. 
BY N. H. WINCHELL AND E. O. ULRICH. 
STRATIGRAPHIC DIVISIONS OF THE LOWER SILURIAN IN MINNESOTA. 
The reader will see by reference to the table of stratigraphic designations in Part I of 
this volume (Introduction, pp. 1 and li) a list of the special names used in the greater part 
of this volume. As, however, the use of the various designations is not entirely uniform in 
the several chapters, and in order that the future student may have some guide in the 
study of these formations in the field, it is necessary to present an exact definition of the 
stratigraphy. 
The published reports of the Minnesota survey have given stratigraphic sections 
at various places, but it has not been found possible heretofore to so adjust them as to 
show any close successional order, aside from that already given. The following might 
be considered as expressing an average composition of the Trenton division of these 
strata in southeastern Minnesota, taken in Olmsted county. It is essentially the same as 
that published in the first annual report, and takes into account only the lithologic 
character of the strata. 
AVERAGE SECTION OF THE TRENTON PERIOD. 
lien OOSe Mra MEM LS ye retereveleestar re ses aray ues ssc ce aictoucresaltuste love eravels eialcrarei a siniaretecerate inte 4 feet. 
ZeVigonesianmlimles comets DUtiemcmesyse stretettcd-weichiaicicieeis cee stcreiciete stele cisiersierorate 30 feet, 10 inches. 
SMS lab yea nas arenll aC eOu Se cyreretrscrareystacin ates tore iste cleiersin cvettiaiayniate voters eiesveietolonershueters 1 foot, 6 inches. 
4 Magnesian limestone, buff...... goOUDHOvAHE RGONS hanonoboudud Suueaauase 11 feet, 6 inches. 
Seal aly alimes COM er yryavesy atime leter craters: aia venaciovs eaal eresocela invest Sainiglove Ravateeepeteistec a 5 feet. 
GirMasnesiane limestone sib itis eves ote) acta au sroeire ery Saeco ercieisr ne oe 20 feet. 
7 Argillo-magnesian limestone with much interbedded shale (or shaly 
limestone). Lowest seen Receptaculites................c0eceees evens 28 feet, 4 inches. 
8 Shales, with thin argillaceous sheets of limestone..................... 18 feet. 
9 Gray or earthy (bluish) limestone, with shaly partings................. 37 feet. 
LOMA termating limestonerand shales aceenetacniseneeicicentlceielencicctemicane 47 feet, 6 inches. 
Tile Gere mi Shall Cie rpeyictosays)/steie x eve/atavtie las cl clarence arene ON Gre otslepevelniaialeuees ronnie area ier aioials 42 feet. 
12 Compact limestone, buff on weathering, blue within, with interbedded 
SIMBA O rats overs cere ree erescio esse nvovsis ercvavew a vidic, achaievaie Coetora er eiske relerere iene ole Be ene 22 feet. 
ORY ale Ghrigeticome ta Mace a SEU er eer oom bac cic qtrit HaiGo cl aORn cpm 267 feet, 8 inches. 
