Stewartry Group

Stewartry Group Stratigraphic range: Cisuralian
Type	Group
Sub-units	Locharbriggs Sandstone Formation, (), Corncockle Sandstone Formation (), , , (), , ()
Underlies	Top everywhere erosional
Overlies	Unconformity over Lower Paleozoic, or Carboniferous
Thickness	up to 610 m (2,000 ft), possibly up to 2,000 m (6,600 ft)
Lithology
Primary	Sandstone, breccia
Other	Conglomerate, siltstone, basalt
Location
Region	Southern Uplands
Country	Scotland
Type section
Named for	Stewartry

The Stewartry Group is a geological group, a stratigraphic unit of mainly breccias and sandstones of Permian age that are found in Southern Scotland. The sequence sits unconformably either on rocks of lower Paleozoic age or Carboniferous strata. The upper boundary of this unit is everywhere erosional.^[1] Rocks of the Stewartry Group form the fill of a series of extensional basins trending NW-SE to N-S across the Southern Uplands.^[2]

Stratigraphy[]

Each of the basins has its own stratigraphy, although the main basinal fill in most cases is a thick sequence of sandstone, that passes either laterally or vertically into breccia.

Thornhill Basin[]

At its base the has a sequence of olivine basalt lavas with some interbedded breccia and sandstone, known as the . The lavas are overlain by either the or the . Both of these breccia formations pass laterally and upwards into aeolian sandstones of the .^[2]

Dumfries Basin[]

The contains breccias and breccio-conglomerates of the , which pass laterally and vertically into aeolian sandstones of the Locharbriggs Sandstone Formation.^[2]

Lochmaben Basin[]

The northwestern part of the also has lavas of the Carron Basalt Formation at the base of the sequence. These are overlain by interbedded silty sandstones and breccio-conglomerates of the . The Hartfield Formation passes up into the thick aeolian sandstones of the Corncockle Sandstone Formation. The uppermost part of the succession is the formed of interbedded siltstones and fine-grained sandstones with layers of coarse-grained sandstone.^[2]

Other basins[]

The contains thick breccio-conglomerates with variable amounts of interbedded sandstones of the . In the , the basal is succeeded by fluvial sandstones of the . Further small outliers of the Stewartry Group are found in the Moffat Basin, the Sanquhar Basin and Snar Valley.^[2]

References[]