The Farallon Trench was an ancient trench on the west coast of North America during the late Cretaceous period. A trench is a long narrow ditch. ... World map showing North America A satellite composite image of North America. ... The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period, about 146 million years ago (Ma), to the beginning of the Paleocene epoch of the Tertiary period (65. ...