Black cliff
The estimated 600 million year old rock of black cliff shows the soft Permian sediments which provided the resistant base where the glacial features were imprinted. Siltstone and sandstone were originally deposited in layers on the bottom of a shallow sea. Slowly the layers became compressed and consolidated into rock under their own weight. Massive earth movements around 500 million years ago caused the rocks to fold and uplift to form a mountain range. Erosion has exposed the rocks we see today and at the southern foot of Black Cliff the folds can be clearly seen.
The estimated 600 million year old rock of black cliff shows the soft Permian sediments which provided the resistant base where the glacial features were imprinted. Siltstone and sandstone were originally deposited in layers on the bottom of a shallow sea. Slowly the layers became compressed and consolidated into rock under their own weight. Massive earth movements around 500 million years ago caused the rocks to fold and uplift to form a mountain range. Erosion has exposed the rocks we see today and at the southern foot of Black Cliff the folds can be clearly seen.
Sugar Loaf
Due to its resemblance to a mass of hard refined sugar, the best known feature in the conservation park is called the sugar loaf. Over thousands of years erosion by wind and rain have given it it's unique cone shape. Southern Australia was covered by an ice cap approximately 280 million years ago and melted approximately 270 million years ago. The sediment was deposited on the bottom of an ancient glacial meltwater lake. The layering and colors of sugar loaf were formed by clay, sand and dropstones that were left on the lake bed. The main portion of this unusual feature is formed by white sands and at the base is a layer of clay and boulders that fell from ice floating across the lake.
Due to its resemblance to a mass of hard refined sugar, the best known feature in the conservation park is called the sugar loaf. Over thousands of years erosion by wind and rain have given it it's unique cone shape. Southern Australia was covered by an ice cap approximately 280 million years ago and melted approximately 270 million years ago. The sediment was deposited on the bottom of an ancient glacial meltwater lake. The layering and colors of sugar loaf were formed by clay, sand and dropstones that were left on the lake bed. The main portion of this unusual feature is formed by white sands and at the base is a layer of clay and boulders that fell from ice floating across the lake.
Chatter Marks
The Hallett Cove Chatter Marks are well known because of the record of events they hold. The chatter marks are a big piece of evidence supporting Professor Ralph Tate's theory that South Australia was a part of the ice age. The Chatter marks were created by a slowly moving glacier, cutting its way through the mountains and plains. Small grains of sand and rocks below the glacier worked to polish the landscape. Larger rocks below the glacier gouged the lines and grooves as they were carried along. The chatter marks help scientists to know in which direction the glacier was traveling.
The Hallett Cove Chatter Marks are well known because of the record of events they hold. The chatter marks are a big piece of evidence supporting Professor Ralph Tate's theory that South Australia was a part of the ice age. The Chatter marks were created by a slowly moving glacier, cutting its way through the mountains and plains. Small grains of sand and rocks below the glacier worked to polish the landscape. Larger rocks below the glacier gouged the lines and grooves as they were carried along. The chatter marks help scientists to know in which direction the glacier was traveling.
Slickenside
A Slickenside is caused by frictional movement between sedimentary rocks along the two sides of a fault. The movement and heat form a smoothly polished surface. The clear parallel lines show the direction of the movement and the surface feels smoother when the hand is moved in the same direction as the fault moved the rock.
A Slickenside is caused by frictional movement between sedimentary rocks along the two sides of a fault. The movement and heat form a smoothly polished surface. The clear parallel lines show the direction of the movement and the surface feels smoother when the hand is moved in the same direction as the fault moved the rock.
Layers of Rock
Hallett Cove Conservation Park has layers of rock everywhere, that show just how old the Earth is. Whilst some evidence has been eroded from the Hallett Cove landscape and lost we can still find five different rock types that were formed at different periods of Earth's history. Sediments such as silt, sand and limestone were deposited 600 million years ago. Movement in the Earth's mantle and crust 500 million years ago deposited sediments which were deeply buried and hardened to form the rocks siltstone, quartzite and limestone. 270 million years ago the ice sheet melted when the weather warmed. The meltwater left behind fine rock flour and this evidence can be found throughout the park. 43 million years ago Australia separated from Antarctica when the super continent Gondwana broke up. 4 million years ago geological evidence to be seen at Hallett Cove shows a warm shallow sea. Shellfish and forminifera and their shells accumulated on the sandy, shallow sea bed. A fossiliferous sandstone was formed and can be found at a number of spots throughout the park. 20 thousand years ago the continental shelf was exposed during the last ice age. 10 thousand years ago the Amphitheater took on its present shape revealing 270 million years of geological time in its layers of rock and sediment.
Hallett Cove Conservation Park has layers of rock everywhere, that show just how old the Earth is. Whilst some evidence has been eroded from the Hallett Cove landscape and lost we can still find five different rock types that were formed at different periods of Earth's history. Sediments such as silt, sand and limestone were deposited 600 million years ago. Movement in the Earth's mantle and crust 500 million years ago deposited sediments which were deeply buried and hardened to form the rocks siltstone, quartzite and limestone. 270 million years ago the ice sheet melted when the weather warmed. The meltwater left behind fine rock flour and this evidence can be found throughout the park. 43 million years ago Australia separated from Antarctica when the super continent Gondwana broke up. 4 million years ago geological evidence to be seen at Hallett Cove shows a warm shallow sea. Shellfish and forminifera and their shells accumulated on the sandy, shallow sea bed. A fossiliferous sandstone was formed and can be found at a number of spots throughout the park. 20 thousand years ago the continental shelf was exposed during the last ice age. 10 thousand years ago the Amphitheater took on its present shape revealing 270 million years of geological time in its layers of rock and sediment.
Fossils
Small marine animals are the only fossils that can be found in the park and were left when the cliffs were covered by the sea. In the riverbeds around the park and some other rock formations, plant and animal fossils (giant snub nose kangaroo) can be found.
Small marine animals are the only fossils that can be found in the park and were left when the cliffs were covered by the sea. In the riverbeds around the park and some other rock formations, plant and animal fossils (giant snub nose kangaroo) can be found.
Glacial History
Around 280 million years ago Hallett Cove was a part of the ice age. The ice glaciation which was apart of Hallett Cove, was determined when the continents were all joined to form one large continent called Gondwana. The super continent called gondwana was part of Australia 280 million years ago. It was covered by an ice cap and it was moving over the south pole. The chatter marks and the scratched and polished bedrock as well as the glacial striations on Black Cliff are the evidence left by the glaciers. Other evidence are boulders that were left behind when the ice thawed. These boulders were bought from far away by the glaciers and bear no resemblance to local rocks. When the ice melted it formed a lake (which no longer exists) but left behind sediment which is responsible for the interesting colors and formation of the sugar loaf