| Precipice Sandstone | |
|---|---|
| Stratigraphic range: Sinemurian to early Pliensbachian ~199–187 Ma | |
 Mount Morgan Mine, where strata of the formation was exposed | |
| Type | Geological formation |
| Unit of | Bundamba Group |
| Sub-units |
|
| Underlies | Evergreen Formation |
| Overlies | |
| Thickness | 175 m (574 ft) |
| Lithology | |
| Primary | Sandstone |
| Other | Siltstone,mudstone |
| Location | |
| Coordinates | 24°18′S150°30′E / 24.3°S 150.5°E /-24.3; 150.5 |
| Approximate paleocoordinates | 58°36′S92°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 ofPrecipice Creek, a tributary of theDawson River |
| Named by | Whitehouse |
  Precipice Sandstone (Australia) | |
ThePrecipice Sandstone an Early Jurassic (Sinemurian to earlyPliensbachian, with possible Hettangian levels) geologicformation of theSurat Basin inNew South Wales andQueensland, eastern Australia, know due to the presence of abundant vertebrate remains & tracks.[1][2][3] This unit includes the previously describedRazorback 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, likeBowen Basin units, in an unconformable manner, resting along the eastern basin margin and theBack Creek Group in the southernComet Platform, while in other areas it directly overlies the TriassicMoolayember 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 theThomson orogeny andNew 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]
The Fireclay Caverns were excavated by theMount 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 revealeddinosaur footprints (preserved as infills) being discovered in 1954.[10] To date, nine different ceiling sections of the Fireclay Caverns have been recognised as containingdinosaur footprints. These have been dated to theEarly 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 theMount Morgan Mine. Clay was mined from within the caverns by pick and shovel, then transferred by underground rail to a brickworks lower in theMount 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 theEarly 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/h and then slowed to 1.8 km/h in association with a slight turn in direction.[15]
After cavern excavations ceased, a colony ofbent-wing bats began inhabiting the caverns. The sections of the caverns containing the bats are inaccessible to protect the bat habitat.
| Genus | Species | Type | Location | Material | Origin | Notes | Images |
|---|---|---|---|---|---|---|---|
| Asterosoma[16] |
| Fodinichnia |
| Radiating bulb-like swelling burrows | Annelid worm, vermiform organism | Freshwater/brackish burrow-like ichnofossils | |
| Conichnus[16] |
|
| trails | Gastropods | Freshwater/brackish fillings-like ichnofossils | ||
| Cylindrichnus[16] |
|
| Long, subconical, weakly curved burrows |
| Freshwater/brackish burrow-like ichnofossils | ||
| Diplocraterion[16] |
| Domichnia | U-shaped burrows |
| Vertical, U-shaped, single-spreiteBurrows; unidirectional or bidirectional spreite, generally continuous, rarely discontinuous. MostDiplocraterion 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] |
| Fodinichnia | Simple, unbranched, horizontal cylinder traces | Saltwater/brackish burrow-like ichnofossils. |  | ||
| Lockeia[16] |
|
| Dwelling traces |
| Marine, brackish or freshwater resting traces ofBivalves. |  | |
| Naktodemasis[16] |
| Fodinichnia | Straight to sinuous, unlined and unbranched burrows |
| Freshwater/Terrestrial burrow-like ichnofossils. | ||
| Palaeophycus[16] |
| Domichnia | Straight or gently curved tubular burrows. |
| Freshwater/brackish burrow-like ichnofossils. |  | |
| Phycosiphon[16] |
| Fodinichnia | Irregularly meandering burrows | Vermiform Animals | Freshwater burrow-like ichnofossils. | ||
| Planolites[16] |
| Pascichnia | Cylindrical or elliptical curved/tortuous trace fossils |
| Freshwater/brackish burrow-like ichnofossils.Planolites is really common in all types of theCiechocinek Formation deposits. It is referred to vermiform deposit-feeders, mainlyPolychaetes, producing activeFodinichnia. It is controversial, since is considered a strictly a junior synonym ofPalaeophycus. |  | |
| Scolicia[16] |
|
| Symmetrical trail or burrow | Gastropods | Freshwater/brackish trail-like ichnofossils |  | |
| Skolithos[16] |
| Domichnia | Cylindrical strands with branches |
| Brackish trace ichnofossils. Interpreted as dwelling structures of vermiform animals, more concretely the Domichnion of a suspension-feeding Worm or Phoronidan. | ||
| Siphonichnus[16] |
| Domichnia | Cylindrical strands with branches |
| Brackish trace ichnofossils. Interpreted as dwelling structures of vermiform animals, more concretely the Domichnion of a suspension-feeding Worm or Phoronidan. | ||
| Taenidium[16] |
| Fodinichnia | Unlined meniscate burrows |
| 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] |
| Tubular Fodinichnia | Tubular Burrows |
| Burrow-like ichnofossils. Large burrow-systems consisting of smooth-walled, essentially cylindrical components. Common sedimentary features areThalassinoides trace fossils in the fissile marlstone to claystone intervals |  | |
| Teichichnus[16] |
| Fodinichnia | Vertical to oblique, unbranched or branched, elongated to arcuate spreite burrow |
| Saltwater/brackish burrow-like ichnofossils. The overall morphology and details of the burrows, in comparison with modern analogues and neoichnological experiments, suggestEchiurans (spoon worms) orHolothurians (sea cucumbers) with a combined suspension- and deposit-feeding behaviour as potential producers. |  |
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|---|
Indeterminate |
| Lower Member | Footprints | ornithischian footprints, unassigned to any concrete ichnogenus, but with resemblance with Anomoepodidae |  | |
|
| Lower Member | Footprints | Ornithischian Footprints, originally suggested as quadrupedal theropod tracks, latter identified as of Ornithischian origin.[20] Up to 130 tracks & 4 short trackways are know. | ||
E. isp. | Fireclay Caverns | Lower Member | Footprints | Medium-sized Theropod Footprints. Currently represent the largest of the prints at Mount Morgan | ||
G. isp. | Fireclay Caverns | Lower Member | Footprints | Small-sized Theropod Footprints | ||
| Plesiosauria[22] | Indeterminate |
| Razorback Beds |
| A Freshwater Plesiosaur that cannot be confidently attributed to any particular plesiosaurian clade | |
| Steropoides[19] | S?. isp | Biloela tracksite | Lower Member | Footprints | Small-sized Ornithischian Footprints | |
Indeterminate |
| Lower Member | Footprints | Possibletheropod footprints, unassigned to any concrete ichnogenus. One morphotype includes large tridactyl prints, up to 24 cm. |  | |
"Indet. 2"[9] | Fireclay Caverns | |||||
"Indet. 3"[9] | Fireclay Caverns | |||||
W. isp. | Fireclay Caverns | Lower Member | Footprints | Small-sized Ornithischian Footprints |
| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
|
|
| Incertae sedis; affinities withBryophyta. | ||
| Incertae sedis; affinities withBryophyta. | ||||
| Affinities with the familySphagnaceae in theSphagnopsida. | ||||
| Affinities with the familyNotothyladaceae in theAnthocerotopsida. | ||||
| Incertae sedis; affinities withBryophyta. This spore is found in Jurassic sediments associated with the polar regions. | ||||
| Affinities with the familyNotothyladaceae in theAnthocerotopsida. Hornwort spores. | ).png) | |||
| Affinities with the familySphagnaceae in theSphagnopsida. "Peat moss" spores, related to genera such asSphagnum that can store large amounts of water. |  |
| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
|
|
| Incertae sedis; affinities withLycopodiopsida | ||
| Affinities with the familyLycopodiaceae in theLycopodiopsida. Lycopod spores, related to herbaceous to arbustive flora common in humid environments. |  | |||
| Affinities with theSelaginellaceae in theLycopsida. |
| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
|
|
| Affinities with theCalamitaceae in theEquisetales. 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 moreEquisetites stems are found. |  |
| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
|
|
| Affinities with the genusSaccoloma, type representative of the familySaccolomataceae. This fern spore resembles those of the living genusSaccoloma, being probably from apantropical genus found in wet, shaded forest areas. |  | |
| Affinities with the familyOsmundaceae in thePolypodiopsida. Near fluvial current ferns, related to the modernOsmunda regalis. | _-_Cape_St._Mary%2527s_Ecological_Reserve%2c_Newfoundland_2019-08-10.jpg) | |||
| Incertae sedis; affinities with thePteridophyta | ||||
| Affinities with the familyCyatheaceae in theCyatheales. Arboreal fern spores. |  | |||
| Incertae sedis; affinities with thePteridophyta | ||||
| Affinities with the familyMatoniaceae in theGleicheniales. | ||||
| Incertae sedis; affinities with thePteridophyta | ||||
| Incertae sedis; affinities with thePteridophyta | ||||
| Incertae sedis; affinities with thePteridophyta | ||||
| Incertae sedis; affinities with thePteridophyta | ||||
| Incertae sedis; affinities with thePteridophyta | ||||
| Affinities with the familyOsmundaceae in the Polypodiopsida. Near fluvial current ferns, related to the modern Osmunda regalis. | ||||
| Affinities with the familyOsmundaceae in thePolypodiopsida. Near fluvial current ferns, related to the modernOsmunda regalis. |
| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
|
|
| Affinities with the familiesPeltaspermaceae,Corystospermaceae orUmkomasiaceae in thePeltaspermales. Pollen of uncertain provenance that can be derived from any of the members of the Peltaspermales. The lack of distinctive characters and poor conservation make this pollen difficult to classify. Arboreal to arbustive seed ferns. | ||
| From the familyCaytoniaceae in theCaytoniales. Caytoniaceae are a complex group of Mesozoic fossil floras that may be related to both Peltaspermales and Ginkgoaceae. |
| Genus | Species | Stratigraphic position | Material | Notes | Images |
|---|---|---|---|---|---|
|
|
| Affinities with theHirmeriellaceae in thePinopsida. | ||
| Affinities with the familyCupressaceae in thePinopsida. Pollen that resembles that of extant genera such as the genusActinostrobus andAustrocedrus, probably derived from dry environments. |  | |||
| Affinities with the familyPodocarpaceae. Pollen from diverse types of Podocarpaceous conifers, that include morphotypes similar to the low arbustiveMicrocachrys and the medium arbustiveLepidothamnus, likely linked with Upland settings |  |