560 Professor Jameson’s Geognostical Description 
It is often disposed in globular distinct concretions, but less fre-- 
quently in those of a tabular or columnar form ; it is seldom 
stratified, and where stratification occurs, the strata frequently 
dip to the east under an angle of 15° to 20°. 
The felspar sometimes assumes the form of clinkstone or of 
claystone^ and occasionally it is simply fine granular, or is more or 
less iron-shot. In these different conditions, it is either simple, or 
includes different minerals, and in various forms. The clink- 
stone, claystone, fine granular felspar, sometimes contain grains 
and crystals of felspar, thus forming clinkstone-porphyry^ clay-- 
stone-porphyry^ and felspar-porphyry ; the iron-shot varieties 
are either porphyritic, forming trap-porphyry of some minera- 
logists, or they contain amygdaloidal portions of calcareous-spar, 
green earth, &c. when they are named amygdaloid"^'* 
The felspar frequently assumes a conglomerated character, 
forming a kind of trap-tif^. This trap-tufi' has sometimes a 
basis of felspar, in which are set variously shaped masses, from 
the size of a pea to several inches in diameter of compact felspar, 
claystone, porphyry, &;c. or these masses are joined together 
without any basis or ground. It is either compact, or is dis- 
tinctly slaty. But the felspar forms, besides porphyry, amygda- 
loid, and trap-tuff, frequently greenstone^ when combined with 
hornblende. The greenstone is generally porphyritic, or in 
the state of green porphyry. In different parts of the hill, 
there are layers of a slate-clay.^ which may also be considered as 
felspar in an earthy soiled condition. 
These various modifications and combinations of felspar, with 
other minerals known under the names of porphyry, amygda- 
loid, trap-tuff, and greenstone, are not arranged every where, 
or even generally, in separate and distinct strata ; on the con- 
trary, they are included in each other, in masses of various 
forms and magnitudes, and the one frequently passes by insen- 
sible gradations into the other. Sometimes balls, or angular por- 
tions of porphyry and amygdaloid, are imbedded in a loosely 
aggregated porphyry or trap- tuff*, forming a rock having a 
strikingly conglomerated character, and illustrating, in an inte- 
* In the amygdaloidal masses of calcareous-spar, angular or roundish portions 
of glance-coal are sometimes met with. 
