The Portland Formation is a geological
formation in
Connecticut and
Massachusetts in the northeastern United States.
[Portland Formation]
- USGS It dates back to the
Early Jurassic period.
[Weishampel et al., 2004, pp.530–532] The formation consists mainly of
sandstone laid down by a series of lakes (in the older half of the formation) and the floodplain of a river (in the younger half). The sedimentary rock layers representing the entire Portland Formation are over thick and were formed over about 4 million years of time, from the
Hettangian
The Hettangian is the earliest age and lowest stage of the Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (My ...
age (lower half) to the late Hettangian and
Sinemurian ages (upper half).
[Olsen, P.E. (2002). ]
In 2016, the paleontologist Robert E. Weems and colleagues suggested the Portland Formation should be elevated to a
geological group
In geology, a group is a lithostratigraphic unit consisting of a series of related formations that have been classified together to form a group. Formations are the fundamental unit of stratigraphy. Groups may sometimes be combined into superg ...
within the Newark Supergroup (as the Portland Group), and thereby replacing the former name "Agawam Group". They also reinstated the Longmeadow Sandstone as a formation (within the uppermost Portland Group); it had earlier been considered identical to the Portland Formation.
Vertebrate paleofauna
Dinosaur coprolites are located in Massachusetts, USA.
Ornithischian tracks, Theropod tracks and Prosauropod tracks are located in Massachusetts and Connecticut, USA.
See also
*
List of dinosaur-bearing rock formations
References
Bibliography
* {{cite book , editor-last=Weishampel , editor-first=David B. , editor-last2=Dodson , editor-first2=Peter , editor-last3=Osmólska , editor-first3=Halszka , year=2004 , title=The Dinosauria, 2nd edition , url=https://books.google.com/books?id=vtZFDb_iw40C , publisher=Berkeley: University of California Press , access-date=2019-02-21 , isbn=0-520-24209-2
Geologic formations of the United States
Jurassic Connecticut
Jurassic Massachusetts
Early Jurassic North America
Jurassic System of North America
Sandstone formations of the United States
Ichnofossiliferous formations