It is composed of trap rock , also known as basalt , an extrusive volcanic rock .
Talcott Mountain is a high point on the Metacomet Ridge , a fault - block ridge that formed 200 million years ago during the Triassic and Jurassic periods .
Talcott Mountain is composed of trap rock , also known as basalt , an extrusive volcanic rock .
Talcott Mountain is a high point on the Metacomet Ridge , a fault - block ridge that formed 200 million years ago during the Triassic and Jurassic periods .