Seaham Quarry facts for kids

Seaham Quarry is a special place in Seaham, Australia. It used to be a quarry where rocks were dug out. Now, it's a protected geological site. This means it's important for studying Earth's history. The rocks here tell an amazing story about ancient ice ages. It was added to the New South Wales State Heritage Register on April 2, 1999, because of its unique scientific value.

What Makes Seaham Quarry Special?

Seaham Quarry is famous for its incredible rock layers. These layers are called varved shales. Imagine a tree trunk with rings that show how old it is. Varved shales are like that, but for ancient mud and silt. They have thin, distinct layers that formed over millions of years. Scientists believe these layers were laid down in a cold, icy environment.

How We Discovered Its Secrets

In 1914, a famous Australian scientist named Professor Edgeworth David first realized that the rocks in the Seaham area were formed by glaciers. Glaciers are huge, slow-moving rivers of ice. Later, another scientist found the perfectly preserved varved shales at Seaham Quarry. These shales quickly became famous around the world.

Professor David even showed samples of these rocks at a big science meeting in Hawaii in 1920. A few years later, he brought other scientists to visit the quarry. In 1925, a sign was put up at the site. It explained the amazing things you could see in the quarry.

Protecting This Important Site

In 1979, the Geological Society of Australia wanted to protect Seaham Quarry. The land was for sale, and they worried it might be developed. So, on April 12, 1979, a temporary order was put in place to protect the site. This gave them time to study it more.

Later that year, on December 14, 1979, a permanent order was made. This meant the site would be protected forever. On April 2, 1999, Seaham Quarry was officially added to the State Heritage Register. This ensures its long-term preservation for science and education.

What Does Seaham Quarry Look Like?

Seaham Quarry is a small, old quarry. It's about 14 kilometers northwest of Raymond Terrace. The quarry walls are not very high, only about one to two meters tall. The rocks you see here are part of something called the Upper Carboniferous Seaham Formation. This means they formed during the Carboniferous period, which was over 300 million years ago!

Layers of Ancient Earth

The rocks at Seaham Quarry are made up of different layers. These include:

• Tillite: This is rock formed from ancient glacial debris. It's basically compacted mud and rocks left behind by glaciers.
• Varved shale: These are the famous layered mudstones, like thin pages in a very old book.
• Conglomerate: Rocks made of different sized pebbles cemented together.
• Sandstone: Rocks made from sand grains.
• Mudstone: Rocks made from fine mud particles.

Scientists have found that the varved shale layers are the thickest and most important. They show how sediments settled in an ancient lake.

What the Layers Tell Us

Scientists have studied these layers closely. They found thin clay layers separated by thinner sand layers. Sometimes, there are small, rounded pebbles mixed in. These pebbles might have been dropped by melting icebergs floating in the ancient lake.

One amazing thing about the quarry is the contorted beds. These are layers of rock that are bent and folded, even though the layers above and below them are flat. Scientists used to think glaciers dragged these layers. Now, they believe it might have been caused by ancient landslides or earthquakes. This shows how powerful Earth's forces were, even millions of years ago.

The layers also tell us about how fast the sediments built up. Early scientists thought each pair of light and dark layers in the varved shales represented one year, like tree rings. If that were true, the rocks at Seaham would have taken about 3,000 years to form! However, later scientists realized it's more complex. The layers might not always represent exactly one year. Still, they give us clues about Earth's ancient climate and how it changed.

Why Seaham Quarry is Important

Seaham Quarry is incredibly important for understanding Earth's history.

• It shows clear evidence that glaciers once covered parts of New South Wales. This was a long, long time ago, over 300 million years back!
• The perfectly preserved varved shales are rare and offer unique insights into ancient environments.
• It's linked to Professor Edgeworth David, a key figure in Australian geology. His work here helped us understand the glacial past of the Hunter River Valley.

The quarry is a natural outdoor classroom. It helps scientists and students learn about geology, climate change, and Earth's ancient past. That's why it's protected for future generations to study and enjoy.