Talbragar fossil site
Encyclopedia
The Talbragar fossil site is a paleontological
site of Jurassic
age in the central west of New South Wales
, Australia
. It lies about 30 km no0rth-east of the town of Gulgong
, and 300 km-north-west of Sydney
. The site has been known for over a century during which it has been extensively excavated to the point of near exhaustion. It is now registered as a Crown Land Reserve
for the preservation of fossil
s; access is by permit, and the collection of rocks and fossil specimens is prohibited. The 4 ha reserve is listed on the Australian Register of the National Estate
.
s and mudstone
s that are part of the Purlawaugh formation. They occur mainly as loose blocks and weathered
shale
s over an area of about 300 m by 80 m, with a thickness of no more than 60 cm. They are thought to be the remnants of sediments from a small freshwater lake, surrounded by forest, which existed about 175 million years ago when Australia was part of Gondwana
. The site is the only Jurassic fish site known in New South Wales.
The fossil material consists principally of the fishes that lived in the lake, as well as plants from the forest, whose remains accumulated in the sediments on the lake bed and were preserved. Among the many species discovered are 16 kinds of plant, eight kinds of fish, several insects and a spider.
Paleontology
Paleontology "old, ancient", ὄν, ὀντ- "being, creature", and λόγος "speech, thought") is the study of prehistoric life. It includes the study of fossils to determine organisms' evolution and interactions with each other and their environments...
site of Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
age in the central west of New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
. It lies about 30 km no0rth-east of the town of Gulgong
Gulgong, New South Wales
Gulgong is a 19th century gold rush town in the Central-West of the Australian state of New South Wales. The town is located about north west of Sydney, and about 30 km north of Mudgee along the Castlereagh Highway. At the 2006 census, Gulgong had a population of 1,907 people...
, and 300 km-north-west of Sydney
Sydney
Sydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
. The site has been known for over a century during which it has been extensively excavated to the point of near exhaustion. It is now registered as a Crown Land Reserve
Nature reserve
A nature reserve is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research...
for the preservation of fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s; access is by permit, and the collection of rocks and fossil specimens is prohibited. The 4 ha reserve is listed on the Australian Register of the National Estate
Register of the National Estate
The Register of the National Estate is a listing of natural and cultural heritage places in Australia. The listing was initially compiled between 1976 and 2003 by the Australian Heritage Commission. The register is now maintained by the Australian Heritage Council...
.
Fossils
The fossil-bearing rocks are fine-grained siltstoneSiltstone
Siltstone is a sedimentary rock which has a grain size in the silt range, finer than sandstone and coarser than claystones.- Description :As its name implies, it is primarily composed of silt sized particles, defined as grains 1/16 - 1/256 mm or 4 to 8 on the Krumbein phi scale...
s and mudstone
Mudstone
Mudstone is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the...
s that are part of the Purlawaugh formation. They occur mainly as loose blocks and weathered
Weathering
Weathering is the breaking down of rocks, soils and minerals as well as artificial materials through contact with the Earth's atmosphere, biota and waters...
shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
s over an area of about 300 m by 80 m, with a thickness of no more than 60 cm. They are thought to be the remnants of sediments from a small freshwater lake, surrounded by forest, which existed about 175 million years ago when Australia was part of Gondwana
Gondwana
In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...
. The site is the only Jurassic fish site known in New South Wales.
The fossil material consists principally of the fishes that lived in the lake, as well as plants from the forest, whose remains accumulated in the sediments on the lake bed and were preserved. Among the many species discovered are 16 kinds of plant, eight kinds of fish, several insects and a spider.