68 TRANSACTIONS OF THE [Fes. 1, 
appears. The following analysis shows how basic the rock is, and 
that the silica is remarkably low for one with orthoclase :— 
Fe O. 
Loss. SiOsg, AlO3 FesO3 CaO. MgO. KO. Na O. Total. 
Specimen 30. . 0.45 41.37 16.25 16.93 12.35 4.57 3.98 4.18 100.08 
Magnet Cove. .5.20 38.93 15.41 9.34 16.49 5.57 1.78 5.27 
a the last analysis (J. F. Williams, Igneous Rocks of Arkansas, 
p. 226), there is additional TiO, 1.62 “FeS, 0.89, PO, 0.35, and 
faves of several other elements, ‘making a total of 100.57. The 
specimen had evidently suffered alteration, but shows some close 
analogies with the first analysis. It is an elaeolite mica syenite, 
the Cove type of Williams. The locality of specimen 30 is near the 
northeast corner of 5 B of map. 
Still further south, at the extreme end of the dike, svenite occurs 
like that at the north. Along the highway it has crambled away 
to sand, as was noted by Haeusser, and only by searching can 
fresh material be found. The slides show it to be like the syenite 
of the northern end, and cancrinite again appears. The porphyritic 
type is also to be had in float material. 
We may say of the dike in general that it is normal elaeolite- 
syenite at its extremes, but that it becomes more basic toward the 
southern portion. It may consist of several different outflows 
along the same line. It uniformly contains aegirine and more 
especially in the contact and southern parts has biotite. It is pene- 
trated in places by subordinate dikes of elaeolite porphyry. The 
analyses bring out forcibly the extraordinary range in composition 
which elaeolite- syenite may take, running down into the extreme 
basie end of the series of rocks. The same thing is shown in Ar- 
kansas, to an even greater degree, by J. F. Williams. This is only 
rendered possible by the intermingling of orthoclase with such basic 
minerals as nepheline and sodalite and by relatively abundant bisili- 
cates. The rock has been consistently called elacolite-syenite through- 
out the text, because it was studied in close association with J. F. 
Williams, by whom the name was preferred for the Arkansas expo- 
sures and is used in work already published. With the decadence 
of the time element in petrographic classification, there is no good 
reason (nor, indeed, ever was) for preserving the names elaeolite 
and nepheline for the same mineral, and it would be far better to 
use the latter term, whichis recognized by the mineralogists. As 
is done by the French, the whole group might better be called 
nepheline-syenite. 
It is unfortunate that the Beemerville exposure is Situated in a 
region where no streams of any size cross it—where no railroads or 
artificial cuts in all probability will ever open it up—and that it is 
quite densely covered with woods over almost its entire extent. 
The conditions are unfavorable for good exposures. 
The Associated Basic Rocks.— As already remarked, it is a 
curious fact that peculiar basic dikes are almost universally asso- 
EE SS eee eee ee ee 
