656 REVIEWS 
ous, or Mississippian series, with the one long known farther north- 
ward, is as follows: 
TYPICAL MISSISSIPPI SECTION ARKANSAS SECTION 
Kaskaskia limestone Boston group 
Aux Vases sandstone Batesville sandstone 
St. Louis limestone Spring Creek limestone 
Augusta limestones Boone chert 
Kinderhook beds (St. Joe marble 
( Sylamore sandstone 
According to this arrangement the former lines of division in the 
Arkansas formations will have to be modified considerably. The 
Kinderhook portion will doubtless need further revision in northern 
Arkansas. | 
A “Geological Reconnaissance of the Coal Fields of Indian Ter- 
ritory,” by Dr. Drake, connects the Arkansas work with that of Kansas 
and Missouri. For the first time we are able to understand what rela- 
tionships the subdivisions that were adopted by the Arkansas geolo- 
gists, for the Coal Measures, have to those recognized in other parts of 
the interior province. The sketch-map accompanying the memoir 
gives the distribution of the formations; and a number of sections 
still farther elucidate the structure of the region. 
A small crystalline area, the Spavinaw granite, discovered by Owen 
forty years ago, is found to be a dike, fifty feet wide, breaking through 
the crest of a low anticline of Silurian limestone. As, however, the 
overlying Lower Carboniferous in the bluffs a few yards away is also 
tilted in the same way as the Silurian strata, the age of the dike is 
regarded as post-Carboniferous. Since Owen mentioned the occur- 
rence nothing further has been made known concerning this granite 
until the recent visit. The results of this examination are important, 
as they set to rest much speculation. As the granite must have been 
intruded under a considerable weight of superincumbent strata, it is 
somewhat surprising that all traces of metamorphic action should 
have escaped notice. The presence of the epidote would indicate 
that contact phenomena should be present, at least, in some slight 
degree. 
The Silurian rocks appear only in a few limited areas in the 
extreme eastern part of the territory. All of these localities are north 
of the Arkansas River. Areas known to exist in the southern portion 
of the territory are omitted. 
