140 TJie AfHerican Geologist. March, i899 
and thus set the standard for American geology and, in a sense, 
became its founder. Ofificial surveys of other states refer to the 
splendid volumes of the New York survey, brought out by 
Hall, Emmons, Vanuxem, Conrad, Mather, Torrey, DeKay, 
Beck, and others, as the criterion of accuracy, in preference to 
the best productions of foreign lands. 
"The New York geologists have made out a classification 
of their older rocks," was the challenge of Sir Charles Lyell, 
"now let them prove the truth of it by means of their fossils." 
This reasonable demand stimulated Hall to give increased 
prominence to the study of paleontology, with brilliant results 
known to the whole scientific world. We do not forget his 
associates, from whose work in stratigraphy and nomenclature 
it is not easy always to mark a line of distinction, but it does 
them no injustice to regard Hall as the founder of "the New 
York system," the main features of which have been generally 
applicable in the United States. Most of the names adopted 
are in current use, e. g., Trenton, Utica, Medina, Clinton. 
N^iagara, Marcellus, Hamilton, etc. These are "type-localities," 
admitting modification as applied to regions similar, if not 
exactly identical: and this elasticity has made the system more 
useful than certain other inflexible ones that were for a time 
its rivals. 
Cartographic methods were extremely imperfect when Hall 
took his place as chief of the New York survey. ]\Iuch of the 
state was inaccurately surveyed, and even several decades 
passed before this hindrance was overcome. Evidently geologic 
mapping needs a trustworthy topographical basis. Ofificial 
obstacles caused delay. -Wide regions lay hidden under forests 
and recent deposits that made it hard to do more than shrewdly 
guess at the underlying rocks. After materials had been slowly 
accumulating for fifty years, Prof. Hall was aided by Dr. W. 
J. McGee in the interpretation of the records thus toilsomely 
gathered: a base map was compiled, geological explorations 
revised, new ones made with a degree of vigor hardly to be 
looked for from an octogenarian, such as Hall had become, 
and at last, 1896, a proof edition was printed mainly as a stimu- 
lus to further research. But even in this confessedly incomplete 
form, the geological map of New York meets the standard of 
excellence better than anvthing else of the kind in this countrv, 
