24 WILLIAM T. BRIGHAM 



shock, like the first, of eleven seconds duration. It was thought that the direction was 

 north-north-east to south-south-Avest. Another report gives the direction as from north- 

 east to south-west, and the duration 20". Hartford, the shock lasted from 20"- GO", and 

 the wave apparently moved from north-west to south-east. 



At Albany. New York, Professor Hough, of the Dudley Observatory, gives the time at 

 IP 15', and the duration 1'. A rumbling noise was heard, and a clock pendulum swino-- 

 ing north and south was made to vibrate east and west. Since 9^ A.M. of the previous 

 day, the barometer had fallen rapidly .7 of an inch. During the shock the mercury in 

 the registering barometer was violently agitated. 



At Cleveland, Ohio, several clocks were stopped, each indicating nearly 11'' 45' A.M. 

 Slight shocks were felt at Richmond, Virginia, and at Dubuque, Iowa.-* 



There were no seismometers in any observatory in New England, and we are again 

 compelled to infer roughl}^ the direction and force. 



It was intended when this enumeration of the New England earthquakes was prepared, 

 to supplement it by a full discussion of the geological features of the regions where these 

 have Ijeen most frequent and severe, and also hy a map of such of the so-called trap re- 

 gions of New England and the adjacent parts of Canada, as present distinct indications of 

 volcanic origin. Our State Reports have ver}^ frequently been prepared by those who, 

 witli an admirable knowledge of general geology, have been deficient in the familiarity 

 with volcanic remains, which only a careful study of both the active and extinct sj'stems 

 of volcanoes can furnish. It is probable that the very general, and much abused term 

 " trap " has been given to indurated and obscure aqueous deposits ; certainly, not enough 

 care has been exercised in distinguishing the various kinds which occur in our well-known 

 dikes and veins. 



Although nearly a century ago attention was called to the phenomena observed at West 

 River Mountain, on the Connecticut River, in New Hampshire,^ yet no vulcanologist (if 

 this term may be used), has ever examined the mountain, although, if the reports then 

 published were correct, masses of slag, rapilli and scoria were abundant, at or near the 

 crater-like suunnit. Montreal has been called an ancient trachytic cone. Gay Head, on 

 Martha's Vineyard, and the Moodus Hill, in Connecticut, have had their volcanic nature 

 affirmed, and denied. And the whole valley of the Connecticut River, seamed with dikes 

 and dotted with eruptive cones, is unstudied as yet. No doubt exists that volcanic agencies 

 have been at work here, in comparatively recent times, for the hardened marble of the Ver- 

 mont l)eds on either side of dikes, show the hot rock Avas an intruder on the limestone 

 deposits. The dikes in the conglomerate, near Boston, show the same subsequent date for 

 some of these fomiations. 



When Mr. Percival attempted to report on the geology of Connecticut, he was much 

 impressed with the remarkable and frequent trap ridges and dikes in the centi-e of the 



J SilUinan's Journal (2), vol. L, p. 434. tion was acponipanieci by a lovid noise, resembling the 



^Meiiinirs American Academy, vol. I (1), p. 312. In Dr. soniid ofa cannon. A hole was founil about six inches in 



D\vi>;lU"s Travels, is the following: — "At Hinsdale, on diameter; a pine tree which stood near it, was partially eov- 



the Connecticut River, in the State of New Hanipsliire, ered 1)V a black mineral substance, forced out of tlie pass.age, 



was an eruption of fire in 17.52, from a volcanic moun- consisting chieily of melted and calcined iron ore, and 



tain, called West River Mountain. This miniature erup- strongly resembling the scoria of a blacksmith forge." 



