112 BULLETIN OF THE ESSEX INSTITUTE. 



Hornblende augite porphyrite, feldspars from one to 

 three inches long, dyke rock. 



Aphanitic diorite dyke rocks. 



Aplitic granite dyke rocks. 



Felsite porphyry dyke rocks (eorhyolite). 



Bostonite porphyry (sanadindyke rock). 



Quartz porphyry dyke rocks (eorhyolite). 



Liperite dyke rock (eorhyolite). 



Vitrophyre dyke rock (eorhyolite). 



Keratophyre lava (anorthoclase rock), a sheet covering 

 the rhyolite breccia and banded rhyolites on Marblehead 

 Neck. 



Paleozoic Era, Carboniferous Period, Permo-Carbon- 

 iferous Epoch. Very coarse ferrugiueous conglomerates 

 and grits, blue shales, sandstones and black limestone, 

 that is fossiliferous. 



Surface deposits. 



Cenozoic Era, Pleistocene Period, Pre-glacial Epoch. 

 Pre-glacial clay beds, covered by glacial boulder till (older 

 diluvium) occurring in long ridges or drums, which lie in 

 the general direction of the rock striations. 



Cenozoic Era, Pleistocene Period, Glacial Epoch. 

 Scratched, grooved, polished and striated surfaces of 

 ledges and stones, drift boulder clays. Terminal moraines 

 as drums and drumlins. Eskers, valley sands and clays 

 deposited in ice dammed seas. This determination may 

 include inter-glacial epochs and a post-glacial epoch. 



Psychozoic Era, Post-Terrace period. Present Epoch. 

 Peat-beds, river alluvium. Evidence of subsidence, sub- 

 merged forest trees, cones, nuts and fruits ; also many 

 hundreds of wino;s and fragments of beetles and other 

 insects submerged to a depth of fourteen and one-half feet 

 below high water mark. For full description, see Bul- 

 letin of the Essex Institute, Vol. xxvi, 1894. 



Peaboi>v Academy of Science, 

 Salem, Marcli 29, 1S97. 



