The quarry is known for terrestrial and freshwater fossils about 335 million years old, from the late Viséan stage of the Mississippian subperiod (Early Carboniferous Period).

Three geological intervals are exposed: the East Kirkton Limestone (oldest), Little Cliff Shale (middle), and Geikie Tuff (youngest).

The East Kirkton Limestone in particular has produced numerous well-preserved fossils of tetrapods (four-limbed vertebrates) and arthropods (multi-legged chitinous invertebrates like millipedes and arachnids).

East Kirkton had been ignored by paleontologists since the 1840s, but Scottish fossil collector Stan Wood managed to procure the land in 1985, sparking a rush of scientific interest.

Notable discoveries include Westlothiana (one of the most reptile-like Mississippian tetrapods), Balanerpeton (a common early representative of amphibians in the group Temnospondyli), and Pulmonoscorpius (the largest known terrestrial scorpion).

The East Kirkton area represents an unconventional environment: dry woodlands and mineral-rich lakes nestled among volcanic cinder cones.

Aquatic animals, though not uncommon, are less diverse than those found in the swampy coal forests and coastal sediments prevalent at other Scottish Carboniferous fossil sites.

[6] East Kirkton presented a contradiction: thick layers of carbonate (limestone) intermingled alongside rarer siliceous (chert) beds, emphasizing how both rock types can occur in close succession.

He supported Hibbert's interpretation, considering the Kirkton quarries to represent large lakes influenced by hot springs on an ancient volcanic plain.

[1][10][13] One notable study in the century since Geikie's paper was by Muir and Walton (1957), who reviewed previous research and investigated the carbonate's microscopic texture and origin in more detail.

[9] East Kirkton's decades of obscurity ended in 1984, when Scottish fossil collector Stan Wood discovered a fragmentary tetrapod skull among the limestone slabs of the quarry's spoil heap.

[19][20] Wood's excavations at East Kirkton, and then-unnamed Westlothiana, were featured in the first episode of Lost Worlds, Vanished Lives, a 1989 BBC documentary hosted by Sir David Attenborough.

In other words, it was an amphibian closely related to amniotes (the group containing dry-adapted tetrapods like reptiles and mammals, with reinforced eggs and thickened skin).

The conference produced a series of over 20 papers published in 1993–94 as "Volcanism and early terrestrial biotas" (volume 84, issues 3–4 of Earth and Environmental Science Transactions of the Royal Society of Edinburgh).

It is equivalent in time to rocks from the upper part (Hopetoun Member) of the West Lothian Oil-Shale Formation, exposed north of Linlithgow.

[30][29][31] By comparison to equivalent oil shale strata, the East Kirkton is estimated to belong to the Brigantian (uppermost Viséan global stage) of the Mississippian Subperiod (the lower part of the Carboniferous Period).

[12] Three distinctive geological intervals can be found at the quarry: the Geikie Tuff (youngest / highest), Little Cliff Shale (middle), and East Kirkton Limestone (oldest / lowest).

The area most likely experienced small intermittent cinder cone eruptions, providing basaltic ash or lava as a predecessor to the tuff material.

Black Shale, coarse tuffaceous limestone, silica (chert and chalcedony), pyrite, gypsum, and tuff beds may occur in some layers.

Hydrogen and oxygen isotope ratios indicate that the chert beds precipitated from meteoric water heated to around 60 °C (140 °F), with a minor amount of mineral recycling after deposition.

[15][37] Another hypothesis, based on strontium isotope trends, is that heat and alkaline groundwater are byproducts of chemical reactions between tuff minerals and carbon dioxide molecules seeping in via meteoric water (such as rain).

[9][36][35] In the reconstructed sequence of spherulite formation, freshwater lakes are supplied with high concentrations of dissolved alkaline minerals and microbial acids.

These conditions encourage the precipitation of fibrous calcite, which accumulates on strands of organic material such as algae or cyanobacteria In the shallow part of a lake.

[36][35] Diagenesis (underground heat and pressure) fractures and warms the calcite after deposition, introducing voids and further reprecipitation within the molds of algal strands.

Faults and cooled lava flows would have contributed to the landscape by diverting rivers and damming lakes,[39] as would the progradation of deltaic systems further east.

The East Kirkton Limestone was deposited at a time and place at the intersection between these two environments, as the expanding dry plateau began to displace the brackish lake, enabling the development of a riparian ecosystem in the Bathgate area.

[28] Chert and pyrite, alongside permineralized plant fossils, may indicate that hot springs were prevalent during the deposition of the East Kirkton Limestone.

In the East Kirkton Limestone, robust plant parts such as gymnosperm branches and Stigmaria roots are often preserved by permineralization (petrification).

Pitus P. withamii East Kirkton Limestone Woody arborescent (tree-sized) gymnosperm trunks up to 50 cm (20 inches) in diameter.

[42] Lycopsida East Kirkton Limestone, Little Cliff Shale Lycopsid leaves and sporophylls referable to Lepidophyllum, Cyperites and Lepidostrobophyllum.