- Usage in publication:
-
- Millbrook Quarry Member*
- Modifications:
-
- Named
- Dominant lithology:
-
- Conglomerate
- Sandstone
- AAPG geologic province:
-
- Piedmont-Blue Ridge province
- Culpeper basin
Summary:
The upper conglomerate and sandstone unit of the Waterfall Formation of Lindholm (1979), is here named the Millbrook Quarry Member for exposures at Millbrook quarry, Va. It consists of cobbles of greenstone and minor quartzite, gneiss, marble, limestone, basalt, and quartz in a sand and silt matrix, and is intercalated with lenses of arkosic sandstone and siltstone. Outcrops are discontinuous and occur along the western margin of the central part of the Culpeper basin. The contact with the underlying Waterfall beds is an apparent disconformity; the upper contact has been removed by erosion. Thickness is 450 m (150 ft) near Millbrook quarry. Age is Early Jurassic (Sinemurian and Pliensbachian) based on palynoflora in the underlying Waterfall beds.
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 ([ ]).