Teachers Guide
Long Reef Geotrail
Burrows
Infilled burrows are common trace fossils in the Bald Hill Claystone. How many different types can you find? How can you differentiate them? What is their relationship to the sediment layers? Are they filled with the same stuff that they burrowed in? What do you think lived there? How did they burrow? Were the organisms feeding or living in the structures, and what do you think they might have been?
Rock structure
How can you distinguish between joint planes and fault planes in the Bald Hill Claystone? Do the faults give any indication of how the rocks moved? Have they all moved in the same direction, and can you visualise a 3-D pattern that relates to all beds and other structures?
Individual sedimentary beds in the Bald Hill Claystone are quite distinct. Can you identify different sorts of vertical relationships between beds and explain how they came about?
Fossils
On some bedding planes there are features that look like squeezed out toothpaste. Can you classify different groups on size, texture, or shape? How might they have been formed? What tests could you apply to your ideas that would support your model?
Plant fossils in the Bald Hill Claystone are common but not easy to find or identify. Look in the loose flaky rocks at the foot of the cliffs or on the edge of the shore platform and you should find enough to develop questions. How many different types are there? What are they composed of? What do you think the environmental conditions were that enabled preservation? What do these fossils tell us about the nature of the landscape when the sediments were deposited?
The alternating layers of grey and reddish-brown claystone in the Bald Hill Claystone have been described at length as ‘fossil soils’ which allegedly demonstrate that the sequence of sediment was deposited on land. Under what conditions might a soil become fossilised? What properties would a fossil soil be expected to have to demonstrate that it was in fact a soil? Can you see anything in these layers that would support or refute this hypothesis?
On some of the bedding planes in the Bald Hill Claystone you may find tracks and trails of invertebrates that lived on the sediment surface. How many different patterns can you find and are there any similar patterns on the modern shore platform or in the beach sand?
Minerals
Between Fishermans Beach and the spit on Long Reef Point there are several small beaches. How does the sand differ from one beach to another, or one part of a beach to another? Explain why this might be? What does it tell us about the relationship between beaches, wave energy, living conditions, and local geology? Hint: you might be helped by photographing the sand with your phone to compare and identify all the different components.
Biosphere interactions with geology
How many direct interactions can you find between organisms living at Long Reef and the rock outcrops? Do these links hasten or slow rock decay and coastal erosion? What do you think the long-term effects might be?
Although Long Reef is an Aquatic Reserve people do still take fish and invertebrates for food or bait, and others collect shells. What do you think the effect of these activities might be in the long term and how