and Volcanic Substances. 241 
erosses the river at Matson’s ford, about thirteen miles 
pone from Philadelphia. It cuts through all es strata in 
rock ; internally bearing no mark of igneous operation. It 
is more like a primitive than a floetz trap. It is found cut- 
ting through with its companions the limestone stratum of 
the river Scuylkill about three miles above the Soapstone 
quarry. ‘This dyke is different from the rocks it adjoins, 
in alli a characters; it is a — heap of unconformable 
ba: . The stone in question, is a pentagonal 
ona t has been (from its ena a “Or consid- 
ered as a eptanitiite trap. Who ever saw a Pentagonal — 
tive trap? Moreover, the rule of morals, is the rule of 
Geology, nosciter a socio. 
I have no other information of any fletz trap until we 
come to the basalt wall near the Yadkin in North-Carolina. 
I have specimens of this ; but I never have been at the spot. 
It is undoubtedly a basalt dyke. 
About a mile from Columbia, (South-Carolina) near 
Rocky branch, a few yards from Dr. Fisher’s mill dam 
the high road, Mr. Vanuxem found a thin vein of trap, (a 
wacke as I think) cutting through the old granite. The 
depth unknown. The vein is about two inches over. 
While the flcetz trap formation is referred to aqueous ori- 
gin, we shall never understand our country: but I appre- 
hend, that opinion has at present few supporters among well 
informed Geologists in Europe. In this country Werner’s 
theory prevails, but its downfal is not far distant. 
Indeed, the i — origin of our Granite formation in its 
present form and , has been made so probable 
by the tions of Hutton, Playfair, Sir James Hall, 
and Dr. M’Culloch, that we shall in my opinion be driven 
to rat. it, notwithstanding the prejudices that as _ stand 
Appendix.—Dr. T. D, Porter has been so good as to 
furnish me with the following additional information. 
