The Wonthaggi Formation is an informal geological

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

in Victoria, Australia whose strata date back to the

Early Cretaceous The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pr ...

. It is part of the Strzelecki Group within the

Gippsland Basin Gippsland is a rural region that makes up the southeastern part of Victoria, Australia, mostly comprising the coastal plains to the rainward (southern) side of the Victorian Alps (the southernmost section of the Great Dividing Range). It covers ...

. Dinosaur remains are among the fossils that have been recovered from the formation.Weishampel, David B; ''et al.'' (2004). "Dinosaur distribution (Early Cretaceous, Australasia)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 573-574. . It is partially equivalent to the Eumeralla Formation.

Geology

The Wonthaggi Formation was deposited within the extensional

rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear de ...

formed between Australia and Antarctica. The lithology primarily consists of fluvially deposited

siliciclastic Siliciclastic (or ''siliclastic'') rocks are clastic noncarbonate sedimentary rocks that are composed primarily of silicate minerals, such as quartz or clay minerals. Siliciclasic rock types include mudrock, sandstone, and conglomerate Conglome ...

s derived from volcanic rocks of the Whitsunday Silicic

Large Igneous Province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation ...

to the East, with suggestions that the sediments either originated from

braided river A braided river, or braided channel, consists of a network of river channels separated by small, often temporary, islands called braid bars or, in English usage, '' aits'' or ''eyots''. Braided streams tend to occur in rivers with high sedime ...

and sheet flood deposits, or

meandering river A meander is one of a series of regular sinuous curves in the channel of a river or other watercourse. It is produced as a watercourse erodes the sediments of an outer, concave bank ( cut bank) and deposits sediments on an inner, convex bank ...

systems on vegetated

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

s. The age of the formation is thought to be

Valanginian In the geologic timescale, the Valanginian is an age or stage of the Early or Lower Cretaceous. It spans between 139.8 ± 3.0 Ma and 132.9 ± 2.0 Ma (million years ago). The Valanginian Stage succeeds the Berriasian Stage of the Lower Cretac ...

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma ( million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is pre ...

, with the Flat Rocks site being late Barremian (~125 Ma) in age, older than the sediments from the Eumeralla Formation, which are thought to be

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ag ...

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± ...

in age.

Vertebrate paleofauna

Indeterminate ornithopod remains are present in Victoria, Australia. Indeterminate megaraptorid remains are present in Victoria, Australia.

References

{{Reflist Geologic formations of Australia Cretaceous System of Australia Early Cretaceous Australia Valanginian Stage Hauterivian Stage Barremian Stage Aptian Stage Sandstone formations Siltstone formations Fluvial deposits Fossiliferous stratigraphic units of Oceania Paleontology in Victoria Geology of Victoria (Australia)

Geology

Vertebrate paleofauna

See also

References