Baltic and Tyle'r-bont Quarries
Geology & landscape
Geological Feature: Karst · Mining / Industrial: Quarry · Geological Period: Carboniferous · Rock Type: Carboniferous Limestone, Limestone
Landscape processes: Fluvial, Karst
Description
Description Baltic Quarry is a site showing a section through the Carboniferous Limestone, here of Courceyan-Holkerian age. The section includes the Llanelly Formation, which contains an unusual clastic facies, namely an alluvial fan development, sandwiched between a karstic surface below and peritidal limestones above. The section shows evidence of, in sequence: emergence, karstification of a limestone surface, gullying and fluvial deposition on that surface, followed by transgression and the return of normal marine conditions. This is a key site for studying stratigraphy and facies changes in Lower Carboniferous rocks. The Tyle'r-bont quarry shows the top of the Oolite Group and Llanelly Formation of the Carboniferous Limestone. Its section complements that of Baltic Quarry. It shows a unique palaeosol development, including five calcrete horizons within the profile (the Tyle'r-bont Pedomcomplex). This lies above a palaeokarstic horizon and below peritidal limestones. Tyle'r-bont is an important site for the study of event-stratigraphy, karstification and soil profiles. Remarks: The site lies within the Brecon Beacons National Park.