Geology and Mineralogy of Salisbury. 253 
For the most part it is easily distinguished ; sometimes, 
however, it might be mistaken for gneiss, and occasionally 
from its soft texture it might be called talcose slate, or 
talco-micaceous rock of Eaton. But such appearances 
are rare. It is often fissile, and easily split into tabular and 
rhomboidal masses. Veins of fetid quartz several inches in 
thickness often intersect it perpendicularly to the strata. It 
contains iron ore, (of which the brown oxide, hematitic and 
argillaceous are most common,) feldspar, graphite, manga- 
nese, sulphur, garnet,staurotide,hornblende,epidote,augite, 
&c. The frequent alternations of granular limestone and 
mica-slate in this town, were noticed by Prof. Silliman in 
a former number of this Journal.* In examining them the 
geologist will be convinced of any thing sooner than of 
‘*‘ regular continuous strata.’ In many instances the slate 
appears in insulated patches lying in the limestone, in 
others the limestone reposes in unstratified beds on the 
slate. They also pass into each other, forming with the 
quartz and mica mingled with it a singular aggregate 
“scarcely capable,’ as Prof. Dewey remarks, “of being 
named, and hardly worth the trouble of doing it.” 
In the last number of this Journal Prof. Dewey de- 
scribes a rock of mica-slate as resembling a pile of huge 
saddletrees ; the convex side uppermost, showing -the ap- 
plication of some force from beneath. ‘There is a rock 
of the same kind in this town, but the convexity is revers- 
ed. How any of the existing theories would account for 
such appearances I know not. The strata are often un- 
dulating or of a zigzag form, the layers being distinctly 
parallel. There are many such facts which confound the 
geological inquirer. We may suppose how such appear- 
ances may have been produced, but how they were may be 
another thing. The imagination can picture an interna! 
fire, heaving the massy granite above the incumbent rocks, 
or a plastic world slowly obeying the laws of aflinity, and 
arranging its solvent materials as attraction dictates, yet 
we might be as far from the fact as ever. 
* Vol. II. p. 211, 
