Rocks of Little Rhody, Part 6: Outcrop of the Newport Neck Formation | Newport, Rhode Island, USA
(Updated on May 26, 2025)
On the Atlantic shoreline. Just seaward of Ocean Avenue, some 300 yd / 275 m east of its T-intersection with Harrison Avenue.
Welcome to beautiful Avalonia, a terrane that was originally associated with the southern supercontinent of Gondwana. Now it's conveniently attached itself to New England, after a long journey across an ancient, long-vanished ocean basin.
This exposure is composed of maroon, oink, greenish, and gray clastic beds, somewhat metamorphosed, that are graded in a way to suggest a turbidite sequence. This is the Newport Neck Formation, thought to be Neoproterozoic or older. It's one small component of the Avalonian section of northeastern North America.
I especially like this shot and the outcrop it shows because the reddish-brown layers extending up from the water's edge. There also seems to be a monoclinal fold—a whitish layer slopes down to a lower horizontal level at right. Is it the "buff-weathering" volcanic-ash tuff also cited for this locale?
A later note: Since I first wrote this, I've come across the following source:
Rast, Nicholas and James W. Skehan. "The Geology of Precambrian Rocks of Newport and Middletown, Rhode Island" (1981). NEIGC Trips, 293.
This field-trip guide is an oldie but a goodie, because it specifically describes the stratigraphy and metamorphic textures of this part of the shoreline.
And of course I also like the fact that it confirms what I wrote above. See Part 7 of this set for a further explication of this site's rock types.
To see the other photos and descriptions in this set, visit my my Rocks of Little Rhody album.
Rocks of Little Rhody, Part 6: Outcrop of the Newport Neck Formation | Newport, Rhode Island, USA
(Updated on May 26, 2025)
On the Atlantic shoreline. Just seaward of Ocean Avenue, some 300 yd / 275 m east of its T-intersection with Harrison Avenue.
Welcome to beautiful Avalonia, a terrane that was originally associated with the southern supercontinent of Gondwana. Now it's conveniently attached itself to New England, after a long journey across an ancient, long-vanished ocean basin.
This exposure is composed of maroon, oink, greenish, and gray clastic beds, somewhat metamorphosed, that are graded in a way to suggest a turbidite sequence. This is the Newport Neck Formation, thought to be Neoproterozoic or older. It's one small component of the Avalonian section of northeastern North America.
I especially like this shot and the outcrop it shows because the reddish-brown layers extending up from the water's edge. There also seems to be a monoclinal fold—a whitish layer slopes down to a lower horizontal level at right. Is it the "buff-weathering" volcanic-ash tuff also cited for this locale?
A later note: Since I first wrote this, I've come across the following source:
Rast, Nicholas and James W. Skehan. "The Geology of Precambrian Rocks of Newport and Middletown, Rhode Island" (1981). NEIGC Trips, 293.
This field-trip guide is an oldie but a goodie, because it specifically describes the stratigraphy and metamorphic textures of this part of the shoreline.
And of course I also like the fact that it confirms what I wrote above. See Part 7 of this set for a further explication of this site's rock types.
To see the other photos and descriptions in this set, visit my my Rocks of Little Rhody album.