a 
> E 
« 
- ri 
4 
a 
RAYMOND: CORRELATION OF THE ORDOVICIAN STRATA. 257 
above), and the Clitambonites bed (zone 6). The zone 7, with its 
large gastropods, particularly the Fusispiras and Trochonemas, Cyclo- 
spira bisulcata, Rafinesquina deltoidea, and Strophomena trilobata, is 
an exact counterpart of the Picton of Ontario. 
The Clitambonites beds of both Ontario and Minnesota are char- 
acterized by the same species of Clitambonites and Parastrophia, and 
there are many more fossils common to the two. 
The Decorah shales of Minnesota have been correlated by Dr. 
Ulrich with the strata above the Leray-Black River and below the 
cystid beds at Kirkfield, Ontario, and on this point we are in agree- 
ment. 
The Stewartville dolomite is not present in Ontario, nor have any 
NORTHERN DOLGEVILLE =PATTERSONVILLE ALBANY 
AY. MINN. ONTARIO if TRENTON CANAJOHARIE SCHENECTADY 
| FALLS 
STEW. ¥. 
fetoey =) 
CO UPPER PICTON Sse UTICA: 
F  EaiEEEEEREEEEEEEEEEEREREEEE EEE 
te te es =f ——_— 
Te Se == LOWER PICTON reo 
Ht Ob rosser eagles ioe el 2S os es oe a Bd =a = 
wit MORES Seer PRASOPORA BED Snsatoss CANAJOHARIE== 
F 2 ak [=] 
t= DECORAHL I 1 
{el Catt a ae a imi ; C1 
CURDSVILLE Foo ROCKLAND 
Fig. 1.— Correlation of the sandy and shaly strata of eastern New York with the 
calcareous strata of the more western localities. The strata represented by the 
dots are predominantly sandy shales and sandstones, with subordinate amounts of 
black shale. The next beds below are very fine-grained shales, usually very dark 
in color, and the remaining strata, represented by the “‘brick”’ design, are prin- 
cipally limestone. For Plat’ville, read Platteville. 
of its characteristic fossils been found there. In Minnesota a part 
of the Prosser fauna passes over into the Stewartville, and there does 
not appear to have been any break in the sedimentary record, so that 
there was apparently here a persistence of limestone deposition after 
it had ceased in Ontario. 
Reviewing what has been said of the preceding sections, it will be 
seen how the shales in their westward progress transgressed higher and 
