The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in winter. Each pair of layers is called a varve and represents one year. The sediments of the Green River Formation present a continuous record of six million years. The mean thickness of a varve here is 0.18 mm, with a minimum thickness of 0.014 mm and maximum of 9.8 mm.
The sedimentary layers were formed in a large area named for the Green River, a tributary of the Colorado River. The three separate basins lie around the Uinta Mountains of northeastern Utah:
- an area in northwestern Colorado east of the Uintas
- a larger area in the southwest corner of Wyoming just north of the Uintas known as Lake Gosiute
- the largest area, in northeastern Utah and western Colorado south of the Uintas, known as Lake Uinta
Fossil Butte National Monument in Lincoln County, Wyoming is in a part of the formation known as Fossil Lake because of its abundance of exceptionally well preserved fish fossils.
Read more about Green River Formation: Lithology and Formation, Cyclicity, Fossil Zones, Oil Shale, Trona and Nahcolite
Famous quotes containing the words green, river and/or formation:
“When the tea is brought at five o’clock,
And all the neat curtains are drawn with care,
The little black cat with bright green eyes
Is suddenly purring there.”
—Harold Monro (1879–1932)
“Our trouble is that we drink too much tea. I see in this the slow revenge of the Orient, which has diverted the Yellow River down our throats.”
—J.B. (John Boynton)
“I want you to consider this distinction as you go forward in life. Being male is not enough; being a man is a right to be earned and an honor to be cherished. I cannot tell you how to earn that right or deserve that honor. . . but I can tell you that the formation of your manhood must be a conscious act governed by the highest vision of the man you want to be.”
—Kent Nerburn (20th century)