Mountains the size of the Himalayas once dominated the horizon west of the Hudson River. A massive lake rimmed with volcanoes and steaming vents once stretched from Lancaster, PA to New Haven, CT. What we know as the Jersey shore was once in Philadelphia. The remains of these extraordinary ancient landscapes lie beneath our feet, and have been the focus of much research. Studies of this region have profoundly influenced our understanding of fundamental natural processes occurring throughout the world. From building mountains to rifting continents and forming oceans, we’ll examine some of this globally-relevant evidence—much of it gathered within a day’s drive of the Observatory.