& Association of ee Geologists. 173 i 
Prof. Hitchcock thought that the steps of the new red sand- 
stone of the Connecticut valley were the result of the fractures ~~ 
referred to by Prof. Mather—they were nearly coincident with 
the strike of the strata, as if caused by elevatory movements. > 
found difficulty in distinguishing between fissures pr 
mechanical violence and joints prop rly so called; he aed , 
those of the a omerate as *mecha anieal, those of the slates as 
chemical. es occurred to iy as worthy of notice ; the 
first was ae" a Vipks of greenstone “crossed. by parallel transverse a 
Planes two or three feet apart and at right les to the strike of ¢ 
the vein. The second case seeme to throw some light on von ‘ 
origin of this class of phenomena; ‘occurred ina bed of the — 
common blue diluvial clay—the horizontal layers were uni Seed, * . a) 
but some of them were divided into double rhombs. The rene de” 
iments of Mr. sno of | land, in the la nina 
ie explain this structure. 
noc es io great 
fhe of the Conn t valley. 
: , Jr. had found thi 
‘3% ttton in the argillaceous sandst 
t 
Hartford, in necticut, where this variety of sandstone is : 
used for flagstone. Many of the jo parallel to this on 
_ structure are filled with carbone of ime. 
_. Dr. C. T. Jackson stated that the great tapykeaali or is ‘¥ 
tia had the perpendicular eidicmeenis in a hi, 
the smaller dykes this structure prevails from sidé to side of the — 
ayke, rpendicular to the walls. He thought that ll cases an 
e phenomena were ae De to the way in which the dykes - 
cooled—the structure being pe fen le to the ae, fas toss 
the narrow dykes cooled hod to side, and the heavy 
ones from the upper surface downward. a * 
Prof. Henry D. Rogers remarked, that the trap dykes of 
wer 
Pennsylvania d the megtaing iron ore of Ne io 
' * As this paper. of Prof. Bailey is to appear in full, a plates, in the October 
No. of this Journal, it has bee fompt bere any abate 
of his remarks before —— 2g a 
< 
he “y - + ¥2 a 
io i 
