The Ballagan Formation was historically known as the Cementstone Group,[3][4] but more recently it has been placed as the middle formation of the
Inverclyde Group.[5] This change was motivated by the recognition that the youngest parts of the Devonian
Upper Old Red Sandstone (now known as the
Kinnesswood Formation) were geologically continuous with the lowest parts of the Lower Carboniferous
Calciferous Sandstone Measures (now known as the Ballagan and
Clyde Sandstone formations). This interval of Devonian-Carboniferous overlap was named the Inverclyde Group, and the
cementstone-rich "drab beds" in the middle of the group were renamed to the Ballagan Formation.[6] In
Lothian, the Ballagan and Clyde Sandstone formations are sometimes known as the Tyninghame Formation.[7]
Fossil sites
Many localities of the Ballagan Formation preserve exceptional fossils. The majority of fossiliferous sites are in the
Midland Valley (particularly the
Scottish Borders and
East Lothian), in the southeast corner of Scotland.[5][8]
One of the earliest sites to be studied was the fish bed at
Foulden, which hosts many well-preserved fish fossils, notably including endemic
actinopterygians (ray-finned fish) and the first complete skeleton of a
rhizodont.[9][10] Plants and arthropods also form a significant portion of Foulden fossils.[11][12][13][14] This site and its fish fossils were publicized by E.I. White in 1927,[15] and further excavations were performed by
Stan Wood in 1980-1981.[16] The Foulden fish bed was the primary theme for volume 76 of the Transactions of the Royal Society of Edinburgh: Earth Sciences journal, published in 1985.[16][17][18]
Willie's Hole, near
Chirnside, is another site known for its high quality of preservation. It was initially recognized for its
crustacean fossils, forming "shrimp beds" akin to those observed throughout the later Scottish Carboniferous.[19] Willie's Hole has continued to produce well-preserved fossils of
arthropods, fish, and partial tetrapod skeletons.[5][20][21][22]
By far the largest exposures of the Ballagan Formation occur along the coastal end cliffs of
Burnmouth.[5][23][24] Tetrapod, fish, and arthropod fragments are common in several layers at Burnmouth, not just in fine-grained
overbank deposits[20][22][25][26] but also coarse
river channelconglomerates, an unusual mode of preservation.[27][28]
Some sites are also found along the west coast of Scotland. Auchenreoch Glen, near
Dumbarton, was the collection site for the nearly complete type fossil of Pederpes finneyae, which was the oldest named tetrapod of the Carboniferous upon its discovery.[36] Diverse assemblages of fish teeth and other
microfossils have been found at
Ayrshire[37][31] and at Hawk's Nib and Mill Hole, on the
Isle of Bute.[38]
Paleobiota
The Ballagan Formation preserves a plethora of
tetrapod, fish, and
invertebrate fossils, reconstructing one of the most diverse continental ecosystems known from the Tournaisian stage. A variety of plant megafossils and spores are known from the Ballagan Formation.[11][39][37][40][41]
^Andrews, Julian A.; Ghulam, Nabi (1994). "Lithostratigraphy of the Dinantian Inverclyde and Strathclyde Groups, Cockburnspath Outlier, East Lothian – North Berwickshire". Scottish Journal of Geology. 30 (2): 105–119.
doi:
10.1144/sjg30020105.
S2CID129170097.
The Ballagan Formation was historically known as the Cementstone Group,[3][4] but more recently it has been placed as the middle formation of the
Inverclyde Group.[5] This change was motivated by the recognition that the youngest parts of the Devonian
Upper Old Red Sandstone (now known as the
Kinnesswood Formation) were geologically continuous with the lowest parts of the Lower Carboniferous
Calciferous Sandstone Measures (now known as the Ballagan and
Clyde Sandstone formations). This interval of Devonian-Carboniferous overlap was named the Inverclyde Group, and the
cementstone-rich "drab beds" in the middle of the group were renamed to the Ballagan Formation.[6] In
Lothian, the Ballagan and Clyde Sandstone formations are sometimes known as the Tyninghame Formation.[7]
Fossil sites
Many localities of the Ballagan Formation preserve exceptional fossils. The majority of fossiliferous sites are in the
Midland Valley (particularly the
Scottish Borders and
East Lothian), in the southeast corner of Scotland.[5][8]
One of the earliest sites to be studied was the fish bed at
Foulden, which hosts many well-preserved fish fossils, notably including endemic
actinopterygians (ray-finned fish) and the first complete skeleton of a
rhizodont.[9][10] Plants and arthropods also form a significant portion of Foulden fossils.[11][12][13][14] This site and its fish fossils were publicized by E.I. White in 1927,[15] and further excavations were performed by
Stan Wood in 1980-1981.[16] The Foulden fish bed was the primary theme for volume 76 of the Transactions of the Royal Society of Edinburgh: Earth Sciences journal, published in 1985.[16][17][18]
Willie's Hole, near
Chirnside, is another site known for its high quality of preservation. It was initially recognized for its
crustacean fossils, forming "shrimp beds" akin to those observed throughout the later Scottish Carboniferous.[19] Willie's Hole has continued to produce well-preserved fossils of
arthropods, fish, and partial tetrapod skeletons.[5][20][21][22]
By far the largest exposures of the Ballagan Formation occur along the coastal end cliffs of
Burnmouth.[5][23][24] Tetrapod, fish, and arthropod fragments are common in several layers at Burnmouth, not just in fine-grained
overbank deposits[20][22][25][26] but also coarse
river channelconglomerates, an unusual mode of preservation.[27][28]
Some sites are also found along the west coast of Scotland. Auchenreoch Glen, near
Dumbarton, was the collection site for the nearly complete type fossil of Pederpes finneyae, which was the oldest named tetrapod of the Carboniferous upon its discovery.[36] Diverse assemblages of fish teeth and other
microfossils have been found at
Ayrshire[37][31] and at Hawk's Nib and Mill Hole, on the
Isle of Bute.[38]
Paleobiota
The Ballagan Formation preserves a plethora of
tetrapod, fish, and
invertebrate fossils, reconstructing one of the most diverse continental ecosystems known from the Tournaisian stage. A variety of plant megafossils and spores are known from the Ballagan Formation.[11][39][37][40][41]
^Andrews, Julian A.; Ghulam, Nabi (1994). "Lithostratigraphy of the Dinantian Inverclyde and Strathclyde Groups, Cockburnspath Outlier, East Lothian – North Berwickshire". Scottish Journal of Geology. 30 (2): 105–119.
doi:
10.1144/sjg30020105.
S2CID129170097.