Precipice Sandstone

Precipice Sandstone
Stratigraphic range: Sinemurian to early Pliensbachian ~199–187 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Mount Morgan Mine, where strata of the formation was exposed
Type	Geological formation
Unit of	Bundamba Group
Sub-units	Lower Member Upper Member
Underlies	Evergreen Formation
Overlies	Basement Moolayember Formation
Thickness	175 m (574 ft)
Lithology
Primary	Sandstone
Other	Siltstone, mudstone
Location
Coordinates	24°18′S 150°30′E / 24.3°S 150.5°E / -24.3; 150.5
Approximate paleocoordinates	58°36′S 92°24′E / 58.6°S 92.4°E / -58.6; 92.4
Region	Queensland  New South Wales
Country	Australia
Extent	Surat Basin
Type section
Named for	Sandstone cliffs in the gorge of Precipice Creek, a tributary of the Dawson River
Named by	Whitehouse
Precipice Sandstone (Australia)

The Precipice Sandstone an Early Jurassic (Sinemurian to early Pliensbachian, with possible Hettangian levels) geologic formation of the Surat Basin in New South Wales and Queensland, eastern Australia, know due to the presence of abundant vertebrate remains & tracks.^[1][2][3] This unit includes the previously described Razorback beds.^[4] This unit represents a major, almost primary, source of hydrocarbons in the region, with a Potential CO2 reservoir of up to 70m.^[5] It was deposited on top of older sediments, like Bowen Basin units, in an unconformable manner, resting along the eastern basin margin and the Back Creek Group in the southern Comet Platform, while in other areas it directly overlies the Triassic Moolayember Formation & Callide Coal Measures, being deposited in a comparatively stable basin.^[3] Isopach maps of the Precipice Sandstone indicate two distinct areas of sediment accumulation, suggesting two separate depocentres filled from different source regions during the Sinemurian, with the Thomson orogeny and New England Orogen hinterlands as possible ones.^[6] This unit represented a fluvial-palustrine-lacustrine braided channel north-flowing succession, that seem to have debouch into a shallow restricted tidal/wave influenced marine embayment, marked at areas like Woleebee Creek.^[7] Paleoenvironment-wise, it represents a hinterland rich in vegetation, hinting at wet environments like swamps, where agglutinated foraminifera suggests marine flooding and drier conditions or the encroachment of seawater onto coastal areas.^[8]

Fireclay Caverns

The Fireclay Caverns were excavated by the Mount Morgan Mine to provide clay for its brickworks resulting in very large openings that measure between 4-12 metres in height from the cave floor.^[9] Excavation of the caverns ceased when the mine brickworks were decommissioned in the early 1900s.^[10] Erosion revealed dinosaur footprints (preserved as infills) being discovered in 1954.^[10] To date, nine different ceiling sections of the Fireclay Caverns have been recognised as containing dinosaur footprints. These have been dated to the Early Jurassic (Sinemurian) ~195 million years ago.^[9] Walkways and stairs had been constructed in 2010 to provide access to the dinosaur footprints ^[11] as part of the mine site tours. The site was closed to access in 2011 due to ceiling erosion posing a significant risk to public safety.^[9]

The Fireclay Caverns were excavated to supply clay to brickworks of the Mount Morgan Mine. Clay was mined from within the caverns by pick and shovel, then transferred by underground rail to a brickworks lower in the Mount Morgan Mine site. Excavation from the caverns ceased when their clay was no longer required by the mine. After cavern excavations ceased, clay progressively fell from the cavern ceilings, revealing rock ceilings above. In 1954, HRE Staines, a Mount Morgan Limited geologist, identified dinosaur footprints in the rock ceilings.^[10][12] Over 300 such footprints have been identified on the cavern ceilings dated to the Early Jurassic (Sinemurian) ~195 million years ago.^[13][14] 2024 represents the 70th anniversary of when Ross Staines published Australia's first dinosaur trackway-consisting of four footprints. ^[10][14] To celebrate, previously unpublished archival photographs (c. 1954) enabled a re-examination of Staines' original trackway, from which two additional footprints were revealed^[15].Analyses indicated the trackmaker exhibited a walking gait, initially walking at ~3.8 km/hr and then slowed to 1.8 km/hr in association with a slight turn in direction.^[15]

After cavern excavations ceased, a colony of bent-wing bats began inhabiting the caverns. The sections of the caverns containing the bats are inaccessible to protect the bat habitat.

Biota

Invertebrates

Genus	Species	Type	Location	Material	Origin	Notes	Images
Asterosoma[16]	Asterosoma isp.	Fodinichnia	Chinchilla 4 Borehole Condabri MB9-H Borehole Kenya East GW7 Borehole Moonie 31 Borehole Moonie 34 Borehole Reedy Creek MB3-H Borehole Roma 8 Borehole Taroom 17 Borehole West Wandoan 1 Borehole Woleebee Creek GW4 Borehole	Radiating bulb-like swelling burrows	Annelid worm, vermiform organism	Freshwater/Blackish burrow-like ichnofossils
Conichnus[16]	Conichnus isp.	Domichnia Cubichnia		trails	Gastropods	Freshwater/Blackish fillings-like ichnofossils
Cylindrichnus[16]	Cylindrichnus isp.	Domichnia		Long, subconical, weakly curved burrows	Anemones Polychaete worms	Freshwater/Blackish burrow-like ichnofossils
Diplocraterion[16]	Diplocraterion parallelum	Domichnia		U-shaped burrows	Polychaeta annelids (Axiothella, Abarenicola and Scolecolepis) Sipunculans (Sipunculus) Enteropneustans (Balanoglossus) Echiurans (Urechis).	Marine-Mangroove Vertical, U-shaped, single-spreite Burrows; unidirectional or bidirectional spreite, generally continuous, rarely discontinuous. Most Diplocraterion show only protrusive spreiten, like the local ones, produced under predominantly erosive conditions where the organism was constantly burrowing deeper into the substrate as sediment was eroded from the top.
Helminthopsis[16]	Helminthopsis isp.	Fodinichnia		Simple, unbranched, horizontal cylinder traces	Polychaetes Priapulids	Saltwater/Blackish burrow-like ichnofossils.
Lockeia[16]	Lockeia amygdaloides Lockeia isp.	Cubichnia Domichnia		Dwelling traces	Bivalves	Marine, brackish or freshwater resting traces of Bivalves.
Naktodemasis[16]	Naktodemasis isp.	Fodinichnia		Straight to sinuous, unlined and unbranched burrows	Soil bugs Cicada nymphs Scarabaeid beetle larvae	Freshwater/Terrestrial burrow-like ichnofossils.
Palaeophycus[16]	Palaeophycus tubularis	Domichnia		Straight or gently curved tubular burrows.	Polychaetes Semiaquatic Insects (Orthoptera and Hemiptera) Semiaquatic and non-aquatic Beetles.	Freshwater/Blackish burrow-like ichnofossils.
Phycosiphon[16]	Phycosiphon isp.	Fodinichnia		Irregularly meandering burrows	Vermiform Animals	Freshwater burrow-like ichnofossils.
Planolites[16]	Planolites montanus Planolites beverleyensis Planolites isp.	Pascichnia		Cylindrical or elliptical curved/tortuous trace fossils	Polychaetes Insects	Freshwater/Blackish burrow-like ichnofossils. Planolites is really common in all types of the Ciechocinek Formation deposits. It is referred to vermiform deposit-feeders, mainly Polychaetes, producing active Fodinichnia. It is controversial, since is considered a strictly a junior synonym of Palaeophycus.
Scolicia[16]	Scolicia isp.	Cubichnia		Symmetrical trail or burrow	Gastropods	Freshwater/Blackish trail-like ichnofossils
Skolithos[16]	Skolithos isp.	Domichnia		Cylindrical strands with branches	Polychaetes Phoronidans	Blackish trace ichnofossils. Interpreted as dwelling structures of vermiform animals, more concretely the Domichnion of a suspension-feeding Worm or Phoronidan.
Siphonichnus[16]	Siphonichnus ophthalmoides	Domichnia		Cylindrical strands with branches	Polychaetes Phoronidans	Blackish trace ichnofossils. Interpreted as dwelling structures of vermiform animals, more concretely the Domichnion of a suspension-feeding Worm or Phoronidan.
Taenidium[16]	Taenidium serpentinum Taenidium isp.	Fodinichnia		Unlined meniscate burrows	Deposit-feeding Sipuncula Polychaetes Phoronidans	Freshwater/Blackish burrow-like ichnofossils. Taenidium is a meniscate backfill structure, usually considered to be produced by an animal progressing axially through the sediment and depositing alternating packets of differently constituted sediment behind it as it moves forward.
Thalassinoides[16]	Thalassinoides isp.	Tubular Fodinichnia		Tubular Burrows	Thalassinidea Several Crustaceans (Anomura, Decapoda) Annelids (Polychaeta Sipuncula Dipnoi	Burrow-like ichnofossils. Large burrow-systems consisting of smooth-walled, essentially cylindrical components. Common sedimentary features are Thalassinoides trace fossils in the fissile marlstone to claystone intervals
Teichichnus[16]	Teichichnus isp.	Fodinichnia		Vertical to oblique, unbranched or branched, elongated to arcuate spreite burrow	Polychaetes Dwelling Echiurans Dwelling Holothurians.	Saltwater/Blackish burrow-like ichnofossils. The overall morphology and details of the burrows, in comparison with modern analogues and neoichnological experiments, suggest Echiurans (spoon worms) or Holothurians (sea cucumbers) with a combined suspension- and deposit-feeding behaviour as potential producers.

Vertebrata

Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Anomoepodidae[17]	Anomoepodidae ichnog. indeterminate	Biloela	Lower Member	Footprints	ornithischian footprints, unassigned to any concrete ichnogenus, but with resemblance with Anomoepodidae
Anomoepus[15][18]	Anomoepus scambus Anomoepus ispp.	Carnarvon Gorge Fireclay Caverns Mount Morgan	Lower Member	Footprints	Ornithischian Footprints, originally suggested as quadrupedal theropod tracks, latter identified as of Ornithischian origin.[19] Up to 130 tracks & 4 short trackways are know.
Eubrontes[20]	Eubrontes isp.	Fireclay Caverns	Lower Member	Footprints	Medium-sized Theropod Footprints. Currently represent the largest of the prints at Mount Morgan
Grallator[20]	Grallator isp.	Fireclay Caverns	Lower Member	Footprints	Small-sized Theropod Footprints
Plesiosauria[21]	Indeterminate	Mount Morgan	Razorback Beds	QM F3983-QM F5500, single disarticulated skeleton preserved as natural moulds	A Freshwater Plesiosaur that cannot be confidently attributed to any particular plesiosaurian clade
Theropodipedia[1][22]	Theropodipedia ichnog. indeterminate	Callide Mine Mount Morgan	Lower Member	Footprints	Possible theropod footprints, unassigned to any concrete ichnogenus. One morphotype includes large tridactyl prints, up to 24 cm.
	Theropodipedia "indet. 2"[9]	Fireclay Caverns
	Theropodipedia "indet. 3"[9]	Fireclay Caverns
Wintonopus[20]	Wintonopus isp.	Fireclay Caverns	Lower Member	Footprints	Small-sized Ornithischian Footprints

Bryophyta

Genus	Species	Stratigraphic position	Material	Notes	Images
Annulispora[23]	Annulispora folliculosa Annulispora microannulata	Razorback Beds	Spores	Incertae sedis; affinities with Bryophyta.
Cingutriletes[23]	Cingutriletes spp.			Incertae sedis; affinities with Bryophyta.
Distalanulisporites[23]	Distalanulisporites punctus Distalanulisporites verrucosus			Affinities with the family Sphagnaceae in the Sphagnopsida.
Foraminisporis[23]	Foraminisporis spp.			Affinities with the family Notothyladaceae in the Anthocerotopsida.
Nevesisporites[23]	Nevesisporites vallatus			Incertae sedis; affinities with Bryophyta. This spore is found in Jurassic sediments associated with the polar regions.
Polycingulatisporites[23]	Polycingulatisporites crenulatus Polycingulatisporites densatus Polycingulatisporites mooniensis			Affinities with the family Notothyladaceae in the Anthocerotopsida. Hornwort spores.
Stereisporites[23]	Stereisporites antiquasporites Stereisporites perforatus			Affinities with the family Sphagnaceae in the Sphagnopsida. "Peat moss" spores, related to genera such as Sphagnum that can store large amounts of water.

Lycophyta

Genus	Species	Stratigraphic position	Material	Notes	Images
Apiculatisporis[23]	Apiculatisporis spp.	Razorback Beds	Spores	Incertae sedis; affinities with Lycopodiopsida
Lycopodiumsporites[23]	Lycopodiumsporites austroclavatidites Lycopodiumsporites rosewoodensis			Affinities with the family Lycopodiaceae in the Lycopodiopsida. Lycopod spores, related to herbaceous to arbustive flora common in humid environments.
Neoraistrickia[23]	Neoraistrickia truncata Neoraistrickia spp.			Affinities with the Selaginellaceae in the Lycopsida.

Pteridophyta

Genus	Species	Stratigraphic position	Material	Notes	Images
Calamospora[23]	Calamospora sp spp.	Razorback Beds	Spores	Affinities with the Calamitaceae in the Equisetales. Horsetails are herbaceous flora found in humid environments and are flooding-tolerant. In the sections of the formation such as Korsodde, this genus has small peaks in abundance in the layers where more Equisetites stems are found.

Pteridophyta

Genus	Species	Stratigraphic position	Material	Notes	Images
Annulispora[23]	Annulispora microannulata Annulispora folliculosa	Razorback Beds	Spores	Affinities with the genus Saccoloma, type representative of the family Saccolomataceae. This fern spore resembles those of the living genus Saccoloma, being probably from a pantropical genus found in wet, shaded forest areas.
Baculatisporites[23]	Baculatisporites comaumensis			Affinities with the family Osmundaceae in the Polypodiopsida. Near fluvial current ferns, related to the modern Osmunda regalis.
Camarozonosporites[23]	Camarozonosporites spp.			Incertae sedis; affinities with the Pteridophyta
Cyathidites[23]	Cyathidites australis Cyathidites minor			Affinities with the family Cyatheaceae in the Cyatheales. Arboreal fern spores.
Densoisporites[23]	Densoisporites spp			Incertae sedis; affinities with the Pteridophyta
Dictyophyllidites[23]	Dictyophyllidites mortoni			Affinities with the family Matoniaceae in the Gleicheniales.
Duplexisporites[23]	Duplexisporites gyratus			Incertae sedis; affinities with the Pteridophyta
Foraminisporis[23]	Foraminisporis tribulosus			Incertae sedis; affinities with the Pteridophyta
Foveosporites[23]	Foveosporites sp.			Incertae sedis; affinities with the Pteridophyta
Heliosporites[23]	Heliosporites spp			Incertae sedis; affinities with the Pteridophyta
Indusiisporites [23]	Indusiisporites parvisaccatus			Incertae sedis; affinities with the Pteridophyta
Osmundacidites[23]	Osmundacidites wellmanii			Affinities with the family Osmundaceae in the Polypodiopsida. Near fluvial current ferns, related to the modern Osmunda regalis.
Rugulatisporites[23]	Rugulatisporites spp.			Affinities with the family Osmundaceae in the Polypodiopsida. Near fluvial current ferns, related to the modern Osmunda regalis.

Peltaspermales

Conifers

Genus	Species	Stratigraphic position	Material	Notes	Images
Classopollis[23]	Classopollis classoides Classopollis simplex	Razorback Beds	Pollen	Affinities with the Hirmeriellaceae in the Pinopsida.
Perinopollenites[23]	Perinopollenites sp.			Affinities with the family Cupressaceae in the Pinopsida. Pollen that resembles that of extant genera such as the genus Actinostrobus and Austrocedrus, probably derived from dry environments.
Podosporites[23]	Podosporites spp.			Affinities with the family Podocarpaceae. Pollen from diverse types of Podocarpaceous conifers, that include morphotypes similar to the low arbustive Microcachrys and the medium arbustive Lepidothamnus, likely linked with Upland settings

See also

• List of dinosaur-bearing rock formations
  • List of stratigraphic units with ornithischian tracks
    • Ornithopod tracks

References

This page was last edited on 28 March 2024, at 18:57