Benton. |] ; A16 [February 18, 
General Meetitig. February 18, 1880. 
Vice President, Mr. 8. H. Scudder, in the chair. Forty- 
one persons present. 
The following papers were read :— 
THe AMYGDALOIDAL MELAPHYRE OF BRIGHTON, MAss. 
By E. R. Benton, Pu.D. 
The earliest observations upon the melaphyre rocks commonly 
known as the Brighton Amygdaloid, were published some seventy 
years ago.1 They were made by Mr. S. Godon, a Frenchman, who, 
in the course of his description of the Geology in the vicinity of 
Boston, says of this rock : The conglomerate (7. e., the Roxbury 
pudding-stone,) ‘‘commonly unites with the amygdaloid by an 
insensible transition.” 
In the year 1818,2 J. F. and S. L. Dana described the amygdaloidal 
rocks in the vicinity of Boston, and applied to that variety which is 
found in Brighton, the name variolite. They say with regard to the 
derivation of the name variolite, that this rock “is a variety of 
Amygdaloid, produced by the decomposition of the basis, whereby 
the nodules (7. e., the amygdules), project from the mass; from the 
fancied resemblance to the small-pox (or varioloid) pustule, the name 
Variolite has been given to it.” 
In 1825,3 Dr. J. W. Webster published the statement that the 
passage into each other of the conglomerate and the amygdaloid 
could be satisfactorily observed in several places in the town of 
Brighton. on 
In 1833,4 Dr. Edward Hitchcock in a Report on the Geology of 
Massachusetts called this rock merely a variety of the conglomerate, 
and again in 1835,° and 1844,°® he classes it under Graywacke, mean- 
ing thereby the Roxbury conglomerate, and gives to the amygdaloid 
the name of varioloid wacke. He says: “ Ata quarry about a mile 
southwest of Brighton Meeting House, this varioloid rock may be 
seen passing into conglomerate, showing that it is only a variety of 
the graywacke formation.” 
1Mem. Am. Academy, 111, 150. 1809. 4 Am. Journ. Science, XII, 33. 1833. 
2Mem. Am. Academy, v, 208. 1818. 5 Report on Geol. of Mass., 1835. 
Bost. Journ. Phil., 111, 487. 1825. 6 Final Report on Geol. of Mass., 1841. 
