Geological position of the Catshill group. — Prosser. 351 
for a long period then conditions would be present for the forma- 
tion of a base-level of erosion. The synclinal areas lying at small 
altitudes above the level of the ocean would be less eroded and 
the more elevated portions would be most strongly subjected to 
destruction by subaerial influences. The great depth of the pres- 
ent channel of the Tennessee however may have been attained first 
during the subsequent histoiy of this land area. 
Dr. Hull's paper is a valuable contribution to the geographical 
geology of Tennessee. Whether he would agree with many of 
the statements made in the notes accompanying the present notice 
is another question. It is hoped however that for American read- 
ers these notes will not be found out of place, but will serve to 
suggest some of the lines of research opened by Dr. Hull's paper, 
to those American geologists whose geographical location will per- 
mit the prolonged study of the areas here involved. 
THE GEOLOGICAL POSITION OF THE CATSKILL 
GROUP. 
By Charles S. Prosser, Washing-ton. 
A recent publication by the Geological Societ} r of America* con- 
tains an abstract of a paper by Dr. Henry S. Williams, entitled 
" What is the Carboniferous System?" Professor Williams re- 
fers to the difficult}' that American geologists have experienced in 
attempting to separate the Upper Devonian from the Lower Car- 
boniferous and states that this confusion is due to " a lack of pre- 
cise definition as to the constitution and limitation of the Carbon- 
iferous system."! The works of the early English geologists 
have been carefully studied and it is shown that the system was 
first defined by Conybeare in 1822 as "the rocks which form the 
Pennine. . . .range of mountains in northern England. "J The sec- 
tion of this Pennine Carboniferous system consists of : 1st, 
the upper part of the Old lied sandstone resting upon lower beds 
of Old Red sandstone ; 2d, the "Mountain or Carboniferous lime- 
stone;" 3d, the "Millstone grit and shales"; 4th, the "Coal 
Measures " which are terminated, generally unconformably, by the 
New Red sandstone. The author states liat since ' ' The typical 
section is the section exhibited in the Pennine range ; and as the 
name Carboniferous is a misnomer geologically. .. .and ;is the 
^Bulletin Geol. Soc. Am. Vol. 2, Jan. 3. 1891, pp. 10-20. 
\lbid., p. K3. \Ibid., p. 17. 
