Diatom assemblages in sandy deposits of the 2004 tsunami at Phra Thong Island, Thailand may provide clues to flow conditions during the tsunami. The tsunami deposits contain one or more beds that fine upward, commonly from medium sand to silty very fine sand. Diatom assemblages of the lowermost portion of the deposit predominantly comprise of unbroken beach and subtidal species that live attached to sand grains. The dominant taxa shift to marine plankton species in the middle of the bed and to a mix of freshwater, brackish, and marine species near the top. These trends are consistent with expected changes in current velocities of tsunami through time. During high current velocities, medium sand is deposited; only beach and subtidal benthic diatoms attached to sediment can be incorporated into the tsunami deposit. High shear velocity keeps finer material, including planktonic diatoms in suspension. With decreasing current velocities, finer material including marine plankton can be deposited. Finally, during the lull between tsunami waves, the entrained freshwater, brackish, and marine species settle out with mud and plant trash. Low numbers of broken diatoms in the lower medium sand implies rapid entrainment and deposition, whilst selective breakage of marine plankton (Thalassionema nitzschioides, and Thalassiosira and Coscinodiscus spp.) in the middle portion of the deposit probably results from abrasion in the turbulent current before deposition.

This black and white 64 page education resource examines the dynamic nature of Earth's climate (past and present) and its many influencing factors. Includes student activities. Suitable for secondary Years 7-12.

This document is a professional opinion, presenting an assessment of the macrofossils present in well CKAD0001, located in the Northern Territory in the Georgina Basin.

Legacy product - no abstract available

2004 updated version of Helby, Morgan & Partridge (1987)

This CD-ROM consists of 15 images and explanatory text detailing the nature of dinosaur fossils from Southern Australia as determined by scientists working along Australia's southeast coast. Find out about the dinosaurs that lived at polar latitudes between 120 to 110 million years ago and the fascinating methods they developed to cope with the climate of that region. The images include actual fossils discovered and reconstructions of dinosaurs and the plants and animals with which these dinosaurs were associated. Suitable for primary Years 5-6 an secondary Years 7-12.

The warm greenhouse world of the Late Cretaceous created an ocean that was poorly stratified latitudinally and vertically. Periodically these oceans experienced globally significant events where oxygen minimum zones enveloped the continental margins. Evidence of the effect of one of these Ocean Anoxic Events (OAE?s) is preserved in the southern high latitude strata of the Otway Basin in southeast Australia. During the Late Cretaceous, thick sequences of mudstone-dominated deltaic sediments (the Otway Delta) were deposited in an elongate inlet (ca. 500km wide) between Antarctica and Australia located at least 70?S. The initial Turonian strata of this delta (the Waarre Formation) were deposited in marginal marine delta plain to delta front conditions. The overlying Flaxman Formation and basal Belfast Mudstone preserve evidence of transgressive inner to middle shelf upper delta to prodelta conditions. These Turonian units were subject to periodic dysoxia. The conditions that created this dysoxia in the region were similar to those of the high northern latitude Cretaceous Interior Seaway of North America where intermittent freshwater input and deepening seas caused periods of thermohaline stratification and reduced bottom waters. The overlying Coniacian to Santonian Belfast Mudstone was deposited in outer shelf to upper slope prodelta conditions subject to periodic fluctuations in dysoxia with normal marine salinities. After a period when the oxygen minimum zone contracted, upward-increasing dysoxia in the Belfast Mudstone herald the onset of the Coniacian to Santonian OAE 3. This was the last OAE of the Late Cretaceous, prior to the onset of more ?modern? oceanic conditions. The fluctuations in TOC and hydrogen index in these strata reflect variable dysoxic conditions similar to that reported for OAE 3 in the tropical eastern Atlantic by Hofmann et al. (2003). This periodicity implies a very active and dynamic Late Cretaceous hydrosphere. Eventually, hyposaline conditions or higher sedimentation rates due to upper delta progradation and shallowing in the Santonian caused the local extinction and dissolution of many of the calcareous benthic taxa of the Belfast Mudstone.

The marine and terrestrial palynology of the Middle Jurassic Wanaea verrucosa Zone from the Perseus-3A, Sunrise-2 and Sunset West-1 wells of the North West Shelf of Australia was studied in detail. These three wells represent brackish and shallow marine successions from the Northern Carnarvon and Bonaparte basins respectively. The palynological data derived from these three wells constitute the basis for the formal definition of this important dinoflagellate cyst biozone and its three constituent subzones. The base of the Lower Wanaea verrucosa Subzone is defined by the inception of the index species and is a relatively sparse, low diversity microphytoplankton assemblage; species richness increases up-section. The base of the succeeding Middle Wanaea verrucosa Subzone is defined by the range base of Valvaeodinium spinosum, and the Upper Wanaea verrucosa Subzone is defined by the incoming of the large and distinctive species Endoscrinium kempiae. Other stratigraphically-important datums include the inceptions of ?Bradleyella adela in the lower subzone, Leptodinium spp. and Wanaea lacuna in the middle subzone, and Endoscrinium spp. and Ternia balmei within the upper subzone. Important range tops include Mancodinium semitabulatum and Phallocysta granosa in the middle subzone, and Nannoceratopsis deflandrei in the upper subzone. These and other datums are compared with European ranges to assign a Late Bajocian to Early Bathonian age to the Wanaea verrucosa Zone.

This set of four charts provide an update of the million year numbers assigned to Australian palynological zone boundaries to the latest Geologic Time Scale 2004, authored by Gradstein et al. (2004), over the geological time interval Jurassic to Recent. These charts have been drafted to help display the relationships of the palynological zones to the new timescale and to assist in scaling the zones and subzones, so that most million year ages assigned to the zone boundaries are mostly numbers with not more than one decimal place.

Poster about the Woolshed Creek fossil site discovered by W.B. Clarke in 1844 now being rehabilitated as a geological heritage site, after Madura Parkway roadworks.