CANANDAIGUA AND NAPLES QUADRANGLES 



5 



state map of 1843. This map, which was the summation of some 

 years of observation, served a useful purpose and has been the 

 basis of the maps herewith presented. Accompanying the map of 

 1885 was a brief account of the variations of the faunas ac- 

 cording to the formations represented. Our present data enable 

 and require us to analyze in closer detail variations in sedimen- 

 tation sometimes accompanied and sometimes unaccompanied 

 by variations in faunation. It was made clearly apparent by 

 the writer's long study of the changes in the fauna of the Hamil- 

 ton shales and limestones that very few variations of material 

 importance in the composition of the fauna throughout the en- 

 tire series of these deposits were tangible and this same condi- 

 tion has been shown to prevail in the deposits of this period 

 wherever the sediments maintain the singularly homogeneous 

 character shown in this section. 1 



We have introduced a considerable diversity of coloration on 

 these map sheets but such refined distinctions in sedimentation 

 are now essential to the complete understanding of bionomic con- 

 ditions and stratigraphic changes during the period of deposi- 

 tion of these strata. They are essential also as an aid to the 

 correlation of the rock section here given to that in adjoining 

 regions of the State. Many of the names may prove to serve 

 only a local, perhaps some of them only a temporary, purpose. 

 Certain of the divisions have however a higher value and indi- 

 cate periods of uniform deposition over wide areas in western 

 and central New York. An apology or excuse for the refine- 

 ment of these stratigraphic subdivisions is not necessary. 

 The multiplication of local names as formation terms is one 

 of the imperative accompaniments of progress in the interpre- 

 tation of ancient marine conditions. 



1 The attempt thus made many years ago to determine a basis of subdi- 

 vision in these homogeneous sediments on the basis of the range of the fos- 

 sils, proved as inconsequent as similar efforts subsequently made in this 

 series of sediments. Were one concerned to construct a doll's philosophy 

 from imaginary laws conceived to govern the association of species into 

 faunules the extraordinary uniformity of faunation in these beds should 

 afford an oppugnant problem. 



