The Edith Formation consists of a single upward fining sequence, with a gravel base and overlying sandy to muddy floodplain deposits. It is poorly to moderately consolidated and locally cemented brown gravel, sand, and sandy clay. A typical composition for the basal gravel is 30% quartzite and 40% volcanic rock, with smaller amounts of granite and metamorphic and sedimentary rocks. It contains sparse clasts of densely welded Bandelier Tuff.[1]
The formation extends at least from near Algodones to Albuquerque and forms a distinctive regional marker bed, cropping out along the inner valley escarpment of the Rio Grande. Its thickness is 10–40 feet (3.0–12.2 m). Its upper contact is marked by a diatomite bed and it unconformably rests on the Arroyo Ojito and Sierra Ladrones Formations, with a weakly developed paleosol (fossil soil) at the contact. The base of the formation defines a prominent strath (fossil floodplain) some 40–80 feet (12–24 m) above the present Rio Grande floodplain.[1]
The formation was initially interpreted as a late Pleistocene terrace of the most recent glaciation.[3] More recent work extends its temporal range into the middle Pleistocene.[4]
The unit was first defined by P.W. Lambert in his dissertation on the Quaternary geology of Albuquerque in 1968, and named for nearby Edith Boulevard.[3]
Lambert, P.W. (1968). Quaternary stratigraphy of the Albuquerque area, New Mexico [Ph.D. dissertation]. Albuquerque: University of New Mexico.
Lucas, S.G.; Williamson, T.E.; Sobus, J. (1988). "Late Pleistocene (Rancholabrean) mammals from the Edith Formation, Albuquerque, New Mexico". The New Mexico Journal of Science. 28 (1): 51–58.
