- Usage in publication:
-
- Rockport limestone* member*
- Modifications:
-
- Named
- Dominant lithology:
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- Limestone
- AAPG geologic province:
-
- New England province
Summary:
Rockport limestone member of Rockland formation is described in Knox Co., south-central ME. Author calls it "virtually a marble," although is either too coarse, too dark-colored, or too fractured to be used for ornamental or building purposes. Ranges from dark purplish gray to pure white, the commonest colors being light gray and dark blue gray; banded varieties showing alternate grayish-white and dark blue-gray layers are also very common. Unit is top and major member of Rockland formation. Thickness at least 400 or 500 ft and may reach two or three times this figure.
Source: GNU records (USGS DDS-6; Reston GNULEX).
- Usage in publication:
-
- Rockport Quartzite
- Modifications:
-
- Redescribed
- Dominant lithology:
-
- Quartzite
- AAPG geologic province:
-
- New England province
Summary:
Simplified stratigraphic column for the Islesboro-Rockport belt in eastern ME shows (ascending) Precambrian rocks of Gilkey Harbor, Islesboro Formation, Coombs Limestone, Cambrian Rockport Quartzite and Megunticook(?) Formation. Rockport described as slightly limonite-stained, glassy quartzite and quartzite-clast conglomerate. Unit is about 135 ft thick at Rockport. Contact with Megunticook(?) is unconformable. Age is Early Cambrian.
Source: GNU records (USGS DDS-6; Reston GNULEX).
For more information, please contact Nancy Stamm, Geologic Names Committee Secretary.
Asterisk (*) indicates published by U.S. Geological Survey authors.
"No current usage" (†) implies that a name has been abandoned or has fallen into disuse. Former usage and, if known, replacement name given in parentheses ( ).
Slash (/) indicates name conflicts with nomenclatural guidelines (CSN, 1933; ACSN, 1961, 1970; NACSN, 1983, 2005, 2021). May be explained within brackets ([ ]).