The Kokoamu Greensand is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

found in

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. It is a

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

-bearing, late

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

greensand Greensand or green sand is a sand or sandstone which has a greenish color. This term is specifically applied to shallow marine sediment that contains noticeable quantities of rounded greenish grains. These grains are called ''glauconies'' and co ...

rock unit of the eastern

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

, especially the

Waitaki District Waitaki District is a Districts of New Zealand, territorial authority district that is located in the Canterbury Region, Canterbury and Otago regions of the South Island of New Zealand. It straddles the traditional border between the two regions ...

North Otago North Otago is an area in New Zealand that covers the area of the Otago region between Shag Point and the Waitaki River, and extends inland to the west as far as the village of Omarama (which has experienced rapid growth as a developing centre f ...

and the southern

Canterbury region Canterbury () is a region of New Zealand, located in the central-eastern South Island. The region covers an area of , making it the largest region in the country by area. It is home to a population of The region in its current form was estab ...

. The formation was named by geologist Maxwell Gage in the 1950s. In North Otago it underlies the thicker and harder Otekaike Limestone. The formation gets its green colour from the mineral

glauconite Glauconite is an iron potassium phyllosilicate ( mica group) mineral of characteristic green color which is very friable and has very low weathering resistance. It crystallizes with a monoclinic geometry. Its name is derived from the Greek ...

which forms slowly on the ocean floor.

Fossil content

The formation was laid down in shallow seas some 26-30 million years ago. It contains abundant microfossils of

foraminifera Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...

ostracod Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...

s and

coccolith Coccoliths are individual plates or scales of calcium carbonate formed by coccolithophores (single-celled phytoplankton such as ''Emiliania huxleyi'') and cover the cell surface arranged in the form of a spherical shell, called a '' coccosphere'' ...

s, those of larger marine invertebrates such as the shells of

brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

s and

scallop Scallop () is a common name that encompasses various species of marine bivalve molluscs in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related famili ...

s, as well as

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

echinoderm An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as ...

s, and

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s. Vertebrates found in the formation include

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

penguin Penguins are a group of aquatic flightless birds from the family Spheniscidae () of the order Sphenisciformes (). They live almost exclusively in the Southern Hemisphere. Only one species, the Galápagos penguin, is equatorial, with a sm ...

s and

cetacean Cetacea (; , ) is an infraorder of aquatic mammals belonging to the order Artiodactyla that includes whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively c ...

s. Many of the fossils discovered in the formation are held in the Geology Museum of the

University of Otago The University of Otago () is a public university, public research university, research collegiate university based in Dunedin, Otago, New Zealand. Founded in 1869, Otago is New Zealand's oldest university and one of the oldest universities in ...

. ;Penguins * '' Archaeospheniscus lopdelli'', ''A. lowei'' * '' Duntroonornis parvus''Duntroon
at

Fossilworks Fossilworks was a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. History Fossilworks was cr ...

.org * '' Kairuku waitaki'', ''K. grebneffi'', '' K. waewaeroa'' * '' Korora oliveri''Hakataramea Valley
at

.org * '' Manu antiquus'' * ''

Palaeeudyptes ''Palaeeudyptes'' is an extinct genus of large penguins, currently containing four accepted species. They were probably larger than almost all living penguins, with the smaller species being about the size of an emperor penguin, and the largest s ...

'' * '' Platydyptes amiesi'', ''P. marplesi'', ''P. novaezealandiae'' ;Cetaceans * '' Awamokoa tokarahi'' * '' Horopeta umarere'' * '' Mammalodon hakataramea'' * '' Matapanui waihao'' * '' Tohoraonepu nihokaiwaiu'' * '' Tohoraata waitakiensis'' * '' Tokarahia lophocephalus''

References

{{Reflist Geologic formations of New Zealand Oligocene Oceania Chattian Stage Sandstone formations Paleontology in New Zealand Rock formations of Otago Rock formations of the Canterbury Region Waitaki District

Fossil content

Further reading

References