Tasmania’s fossil bluff
Large signposts in the town of Wynyard on Tasmania’s windy north west coast point the way to a picturesque headland known as Fossil Bluff. Nearby the prominent but extinct volcano of Table Cape stands, a silent reminder of volcanic activity that once devastated the area and produced extensive lava flows which covered the fossil-rich rocks of the Bluff. These rocks with their abundance of preserved animals and plants bear silent testimony to another awesome devastation.
The explorer Strzelecki, in 1845, was the first to notice what he called “raised shell beds”1 at Fossil Bluff.
These rock layers have received much attention from Australian geologists since that time because they contain so many fossils. They are also easy to approach and have a very striking appearance. Most of the geological studies of the area were done in the last half of the 1800s and the early years of the 20th century. During this period, Darwin’s theory of evolution had become the guiding philosophy of geologists and, accordingly, Fossil Bluff was interpreted in evolutionary terms. Since 1905 there have been few studies done on the area and such works usually refer back to those done a century ago.
Rocks and fossils
The rock layers which can be seen in the cliff face at Fossil Bluff have been subdivided by geologists into two units known as the Freestone Cove sandstone and the Fossil Bluff sandstone.2
What can be seen in the rocks is a series of fossil beds which have a large number of different fossils at the base of the cliff. As you proceed up the cliff the fossil beds contain fewer types of fossils and gradually merge into rocks which contain none.3,4
Technically it is described as a breccia or a rock made up of coarse jagged and broken fragments. The shells in the sandstone are held together by iron-rich mud which contains rounded pebbles of yellowish quartz.4 At the base of the cliff (near the high-tide mark) the sandstone rests on top of a rock which contains variously sized pebbles and boulders bound together by a fine blue-grey hardened mud. This boulder-rich rock is known as a conglomerate or a tillite. The actual surface where the sandstone sits on the conglomerate shows much evidence of violent erosion. Its surface has been scoured by currents, and fragments have been broken off and washed up into the sandstone.6
Some of the fossils near the bottom of the sandstone have also been broken and rolled over.7
The Freestone Cove sandstone is full of fossils. Well over 300 species have been identified.2 The list includes algae, forams (single-celled marine animals with tiny shells), corals (solitary and colonial), lace corals (bryozoans), lamp shells (brachiopods), snails (gastropods), barnacles, sea urchins (echinoids) and shark’s teeth.2,8Some decomposed wood has also been found.2
The Fossil Bluff sandstone containing fewer fossils sits on top of the Freestone Cove sandstone. But since they merge into one another, the boundary is somewhat arbitrary. It is this 24 metre (80 foot) thick Fossil Bluff sandstone that forms the bulk of the cliff face. It has been described as a white or grey lime-rich sandstone with some hard bands of impure limestone.2,6In this sandstone several beds rich in one particular fossil species of lace corals (bryozoans) can be found.2
The geologists, Tate and Dennant3 have stated that all species in the Fossil Bluff sandstone occur in the sandstone below it (the Freestone Cove sandstone) except for the sea urchins (echinoids). They also pointed out that there was a reduction in the number of species upwards through the sandstone and that close to the top there were no fossils. Stephens5 was the first to notice leaf impressions and fragments of brown coal in the Fossil Bluff sandstone. A few years later, Johnston9 reported finding several different plant fossils. This sandstone was originally called the Turritella sandstone because it contains an abundance of fossil snails from the genus Turritella. These have a distinctive tapering coiled shell.
The Fossil Bluff sandstone contains corals in some bands as well as snails and bivalves (pelecypods) but brachiopods and cephalopods are rare. The latter is represented by only one species which is similar to the modern cephalopod known as nautilus. Several species of sea urchins (echinoids) are also characteristic of the Fossil Bluff sandstone. Perhaps the most significant fossils found in the sandstone were the remains of a toothed whale and a possum-like marsupial (Prosquabodon davidi and Wynyardia bassiana respectively).2,6
From a distance the most striking feature of Fossil Bluff is the distinct bands of fossils that are consistent laterally for up to 1 km (3,200 feet). At the top of the cliff the sandstones are covered by a weathered, dark, volcanic rock (basalt). On nearby hilltops this basalt lava flow with its associated volcanic ash (tuffs)4 is about 24 metres (80 feet) thick. It seems likely that this basalt flowed as lava from a volcano less than 2 km (1.25 miles) away. The nearby Table Cape is the volcanic plug or remnant core of that volcano. Even though the volcanic rock sits directly on top of the sandstone, the Fossil Bluff rocks do not appear to have even been slightly altered by the heat of lava flowing over them,4 quite an amazing feature if the lava was as hot as flowing lavas are today.
What does all this mean? And why all the interest in a few fossil beds exposed in a Tasmanian cliff? Geologists such as Tate and Dennant, and those who have followed since that time who believe that the bulk of the earth’s sedimentary strata are the result of generally slow processes over millions of years, have problems with Fossil Bluff! Why? Simply because they cannot explain how a land dwelling possum-like marsupial and a deep ocean dwelling whale could be preserved as fossils in the same rock! Since they believe that fossils were formed as animals and plants died and were buried together as sediments filled up their habitats and ecological niches, their view does not usually allow animals which have never lived together, and in fact come from widely separated areas such as land and deep ocean, to be found buried together. All the geologists who have studied the rocks at Fossil Bluff have unanimously concluded the rocks were deposited in an ocean environment.2,9 So what are a whale and a land dwelling marsupial doing together in the rocks at Fossil Bluff? Tate and Dennant vaguely commented ‘the study of … this unique fossil does not permit an explanation of its occurrence other than of its embedment in original soft sediment.’3 That is simply another way of saying ‘we don’t know how it got there’.
There is a better explanation! A watery catastrophe overwhelmed, washed, sorted and buried all these animals and plants together. This is the only explanation which makes sense of all the facts at Fossil Bluff. Such a catastrophe would explain why one sandstone merges into another, i.e. they were not laid down at separate times. The whole sandstone sequence exposed in the Fossil Bluff cliff face would have resulted from one rapid and violent depositional event. The conglomerate beneath the sandstone would probably have been already deposited in an earlier phase of the same watery catastrophe. The scouring and erosion of the surface of this conglomerate is also evidence that this regional watery catastrophe swept across both ocean and land. Its turbulence eroded the surface of the already settling rock layers beneath the violent current.
The jumbled assortment of types of fossils also indicates that the water currents had to be extremely swift and wide ranging to pick up such a varied load as pebbles, mud, large shellfish, sharks, whales and marsupials! Furthermore, water currents are known by observation and experiment to be excellent sorters of the particles and objects they carry along. Once currents are slowed or stopped, the load carried is deposited in layers according to size, weight, and shape of the carried matter. Such an explanation even makes sense of the details observed by geologists at Fossil Bluff.
The bottom layer of sandstone consists of large shells, broken and rolled shells, pebbles and coarse sand, absolutely crammed and thrown together. This layer represents the earliest phase of deposition from the swift and violent water currents. This would have been followed by slower settling out of sediments and fossils as the currents continued to slow down. Thus the fact that the sandstones merge from coarse-grained into fine-grained and the number of fossils species they contain diminishes from a large number at the base to zero at the top is accounted for. The layering (or stratification) of both sediments and fossils is a result of this settling out process that can be experimentally demonstrated in any laboratory with just a simple water tank. This mechanism adequately explains the layers of limey sandstone high up in the cliff sequence that are distinguished by particular fossils of the same shape, size and floatability, be they the snails, Turritella or the lace corals, sea urchins or plant fossils.
The scope and devastation of this watery catastrophe is underlined by the sheer numbers, not only of species but also individuals that are found fossilised in the rocks at Fossil Bluff. Tate and Dennant in 18963 listed some 303 fossil species from Fossil Bluff, a list which did not include the numerous forams and lace corals. A total of 267 species of molluscs are in their list but they went on to note that of those 267 species only 6 were found still to be living. That’s an extinction rate of almost 98%, a very significant catastrophe! The range of environments the fossilised species came from also indicates they were overwhelmed and swept away by a very wide-spread catastrophe. It encompassed a full range of environments from land dwelling creatures through shallow water to deep ocean creatures. While the bulk of fossils are representative of today’s shallow marine environments, the decomposed wood, the brown coal fragments, the fossilised leaves, the fossilised tooth whale and the remains of a possum-like marsupial are indicators of both the scope and the thorough mixing of the waters of this catastrophe. They also indicate that the entire sandstone sequence must have resulted from one rapid depositional event.
But when did this happen? Regretfully neither the fossils nor their rocky graveyard provide us with any definitive or unequivocal answer. The evolutionists (who weren’t there at the time) claim that the sediments of Fossil Bluff were deposited slowly many millions of years ago. Their arguments as to the slow deposition simply do not work. They are poor science indeed.
We do better to turn to the Word of a Witness Who has observed the entire history of the world. God, the Creator, has revealed to man that there was a time when the fountains of the deep were broken up, the windows of the heaven were opened and flood waters covered the entire earth for a year. Such a catastrophe, or its after effects as the earth restabilised from such massive devastation, could easily have produced the rock layers at Fossil Bluff (including the tillite or conglomerate beneath the sandstones) and the nearby Table Cape remnant volcano. While deposition of sandstones and fossils may well have taken less than a day under such catastrophic conditions, both sediments and fossils could well have been carried, mixed and sorted by water currents for considerably longer beforehand.
After deposition, the lava flowed equally rapidly, capped off the still wet sediments and cooled before the dissipated heat could alter the hardening sandstones beneath. The retreating flood waters shaped the present topography and at the eroding coastline the bounds were set for the waters now resident in the seas.
Thus Fossil Bluff stands not as a record of slow evolutionary progress in once living communities fossilised over aeons of time, but as a reminder of the catastrophic death and fossilisation that began with the Flood of Noah.
References and notes
- de Strzelecki, P.E., Physical Description of New South Wales and Van Dieman’s Land, Longman, Brown, Green and Longmans, London, 1845. Return to text.
- Banks, M.R., The stratigraphy of Tasmanian limestones In: Hughes, T.D., Limestones in Tasmania, Mineral Resources Tasmania 10:39–85, 1957. Return to text.
- Tate, R., and Dennant, J., Correlation of the marine Tertiaries of Australia, Part III, South Australia and Tasmania, Transactions of The Royal Society of South Australia 20(1):118–148, 1896. Return to text.
- Johnstone, R.M., Further notes on the Tertiary marine beds of Table Cape, Papers and proceedings of the Royal Society of Tasmania 1876:79–90, 1877. Return to text.
- Stephens, T., Remarks on the geological structure of part of the North Coast of Tasmania, with special reference to the Tertiary marine beds near ‘Table Cape’, Papers and proceedings of the Royal Society of Tasmania 1869:17–21, 1870. Return to text.
- Gee, R.D., 1971, Table Cape, Mineral Resources Tasmania geological survey explanatory report: geological atlas: 1 Mile Series, Zone 7, Sheet no. 22. Return to text.
- Noetling, F., Notes on the glacial beds of Freestone Bluff (Sandy Cove) near Wynyard, Papers and proceedings of the Royal Society of Tasmania 1909:157–169, 1910. Return to text.
- Gill, E.D., Cainozoic, In: Spry, A. and Banks, M.R. (eds), The Geology of Tasmania, Journal Geological Society of Australia 9(2):233–253, 1962. Return to text.
- Johnston, R.M., Systematic Account of the Geology of Tasmania, Hobart, 1888. Return to text.