Derived from the characteristically coloured marls and sandstones which occur beneath the chalk is a late Cretaceous lithostratigraphic group,  particularly along the coast of one of six countries that make up what?
Northern Ireland
Hibernian Greensands Group
The Hibernian Greensands Group is a late Cretaceous lithostratigraphic group (a sequence of rock strata) in Northern Ireland.
 The name is derived from the characteristically coloured marls and sandstones which occur beneath the chalk particularly along the Antrim coast.
 The strata are exposed on or near to both the northern and eastern coasts of Antrim and also between Portrush and Dungiven within County Londonderry.
 Further outcrops occur between Belfast and Lurgan and between Dungannon and Magherafelt.
 The current names replace an earlier situation where the present group was considered to be a formation and each of the present formations was considered a 'member'.
 Several other stratigraphic naming schemes were in use during the nineteenth century and much of the twentieth century.
 Various units were earlier referred to as glauconitic or chloritic marls.
 This group and the overlying Ulster White Limestone Group are the stratigraphical equivalent of the Chalk Group of southern and eastern England.
County Antrim
County Antrim (named after the town of Antrim, from Irish: "Aontroim" , meaning "lone ridge" , )) is one of six counties that form Northern Ireland.
 Adjoined to the north-east shore of Lough Neagh, the county covers an area of 3046 km2 and has a population of about 618,000.
 County Antrim has a population density of 203 people per square kilometer / 526 people per square mile.
 It is also one of the thirty-two traditional counties of Ireland, as well as part of the historic province of Ulster.
Prairie Bluff Formation
The Prairie Bluff Chalk Formation is a geological formation in North America, within the U.S. state of Alabama.
 The chalk was formed by marine sediments deposited along the eastern edge of the Mississippi embayment during the Maastrichtian stage of the Late Cretaceous.
 It is a unit of the Selma Group and marks the end of the Cretaceous in Alabama.
 Evidence has been found within the formation at Braggs, Moscow, and Millers Ferry in Alabama indicating an instantaneous to brief erosional event, most likely a tsunami, at the Cretaceous–Paleogene boundary (K–T boundary).
 It is hypothesized that this event, along with faulting and liquification of the Prairie Bluff Chalk, is related to the meteorite impact at the Chicxulub crater site, directly south, across the Gulf of Mexico, from the formation. Protungulatum
Protungulatum ('first ungulate') is an extinct genus of mammal first found in the Bug Creek Anthills in northeastern Montana.
 The Bug Creek Anthills were initially believed to be Late Cretaceous (latest Maastrichtian) because of the presence of the remains of non-avian dinosaurs and common Cretaceous mammals, but these were later shown to have been reworked from Late Cretaceous strata, and consequently the Bug Creek Anthills are currently believed to be Early Paleocene (Puercan) in age.
 Remains from the Ravenscrag Formation of Saskatchewan, Canada have been assigned to "P. donnae".
 These remains may also be Cretaceous in age, but the age of the Ravenscrag Formation is not entirely certain.
 In 2011, remains of a new species of "Protungulatum", "P. coombsi", from the Hell Creek Formation, which is definitely Late Cretaceous (Maastrichtian) in age, proved that "Protungulatum" was present in both the Cretaceous and the Paleocene.
 It was initially assigned to the order condylarthra, a group of archaic "ungulates", that is now known to be polyphyletic.
 According to Archibald et al. (2011), "Protungulatum" is not even definitely a placental mammal.
 Some studies have found it to be close to Cetartiodactyla, but the most recent analysis helds it to be a non-placental eutherian. Bacton Group
The Bacton Group is a Triassic lithostratigraphic group (a sequence of rock strata) beneath the southern part of the North Sea.
 The name is derived from Bacton on the Norfolk coast.These strata which are up to 600m thick are the offshore equivalent of the Roxby Formation and Sherwood Sandstone Group which occur in northeast England.
 The Group comprises a lower Bunter Shale Formation of red and brown to grey mudstones and an upper Bunter Sandstone Formation of dolomitic sandstones with mudstone interlayers. Ulster White Limestone Group
The Ulster White Limestone Group is a late Cretaceous lithostratigraphic group (a sequence of rock strata) in Northern Ireland.
 The name is derived from the characteristic chalk rock which occurs particularly along the Antrim coast.
 The strata are exposed on or near to both the northern and eastern coasts of Antrim and also between Portrush and Dungiven within County Londonderry.
 Further outcrops occur between Belfast and Lurgan and between Dungannon and Magherafelt.
 The current names replace an earlier situation where the present group was considered to be a formation and each of the present formations was considered a 'member'.
 Several other stratigraphic naming schemes were in use during the nineteenth century and much of the twentieth century.
 This group and the underlying Hibernian Greensands Group are the stratigraphical equivalent of the Chalk Group of southern and eastern England. Milford Haven Group
The Milford Haven Group is a late Silurian to early Devonian lithostratigraphic group (a sequence of rock strata) in west Wales.
 The name is derived from the estuary and town of Milford Haven in south Pembrokeshire.
 The Group comprises calcareous marls with occasional sandstones along with conglomerates and breccias. Purbeck Group
The Purbeck Group is an Upper Jurassic to Lower Cretaceous lithostratigraphic group (a sequence of rock strata) in south-east England.
 The name is derived from the district known as the Isle of Purbeck in Dorset where the strata are exposed in the cliffs west of Swanage. Chalk Group
The Chalk Group (often just called the Chalk) is the lithostratigraphic unit (a certain number of rock strata) which contains the late Cretaceous limestone succession in southern and eastern England.
 The same or similar rock sequences occur across the wider northwest European chalk 'province'.
 It is characterised by thick deposits of chalk, a soft porous white limestone, deposited in a marine environment. Polyglyphanodontia
Polyglyphanodontia is an extinct clade of lizards from the Cretaceous that includes around a dozen genera.
 Polyglyphanodontians were the dominant group of lizards in North America and Asia during the Late Cretaceous.
 Most polyglyphanodontians are Late Cretaceous in age, though the oldest one, "Kuwajimalla kagaensis", is known from the Early Cretaceous (Valanginian to Hauterivian) Kuwajima Formation (Japan).
 Early Cretaceous South American taxon "Tijubina", and possibly also "Olindalacerta", might also fall within Polyglyphanodontia or be closely allied to the group, but if so, they would be the only known Gondwanan examples of an otherwise Laurasian clade.
 They produced a remarkable range of forms.
 Chamopsiids, including "Chamops", were characterized by large, blunt, crushing teeth, and were most likely omnivores. "
Macrocephalosaurus", from the Gobi Desert, was a specialized herbivore; it grew to roughly a meter long and had multicusped, leaf-shaped teeth like those of modern iguanas. "
Polyglyphanodon", from the Maastrichtian of Utah, was another herbivore, but its teeth formed a series of transverse blades, similar to those of "Trilophosaurus". "
Peneteius" had remarkable, multicusped teeth, similar to those of mammals.
 The polyglyphanodontids first appear in the latter part of the Early Cretaceous in North America, and became extinct during the Cretaceous-Paleogene extinction event.
 Polyglyphanodontians closely resembled the teiid lizards, and purported teiid lizards from the Late Cretaceous appear to be polyglyphanodontians.