X 
PREFACE. 
for a second volume are in band, and will be put to press during the next 
year. 
A valuable paper on the minerals of the State, was also prepared by 
Dr. Genth, in 1871, after a full examination of the collections in the 
museum and a visit to many of the most important mineral localities. 
Other brief reports have been submitted from time to time, on matters ot 
special and immediate interest, as the pamphlets on the resources of the 
State, one in English and' one in German, prepared for the Vienna Expo- 
sition. 
PROGRESSIVE THEORETICAL VIEW. 
The following scheme exhibits the progress of theoretical notions 
which have obtained at different times with regard to the classification of 
the formations, — the age and horizon of the rocks in the State. 
MITCHELL. 
EMMONS. 
PRESENT. 
1842. 
1856. 
1875. 
Tertiary. 
f Postplioeene. 
m ! Pliocene. } 
Tee - j Miocene, f 
l Eocene.* 
Quaternary. 
Miocene. ) 
- Ter. 
Eocene. ) 
Secondary. 
1 
Cretaceous. 
Triassic. ) 
Permian, f 
Cretaceous. 
Triassic. 
Transition. 
Taconic. 
j Silurian? 
| Huronian. 
Primitive. 
" 
Gneiss. ) 
' Granite. >- 
Syenite. ). 
Laurentian. 
*Also partly Quaternary, and partly Cretaceous. 
OBJECTS OF THE SURVEY. 
The purpose of the Legislature in establishing a geological survey 
could not be better expressed than in the message of Gov. Graham, in 
18A6 : — “I trust no consideration will induce a longer delay in directing 
an Agricultural, Geological and Mineralogical Survey of the State. Three- 
