Blue Lias facts for kids
The Blue Lias is a special type of rock found mostly in southwest England and parts of south Wales. It's a famous part of the Jurassic Coast, which is a World Heritage Site.
These rocks are part of a larger group called the Lias Group. The Blue Lias is made up of layers of limestone and shale. These layers formed a very long time ago, between 195 and 200 million years ago. This was during the late Triassic and early Jurassic periods. The Blue Lias is well-known for its amazing fossils, especially ammonites. Scientists have also found parts of dinosaurs and a flying reptile called Dimorphodon here.
What is the Blue Lias made of?
The Blue Lias rocks show a pattern of alternating layers. You'll see layers of limestone (which sometimes has a bit of clay) and then layers of mudstone. These alternating layers are like stripes in the rock.
Scientists believe these stripes were caused by small changes in Earth's climate. These changes are linked to something called Milankovitch cycles. These cycles describe how the Earth's orbit and tilt change over very long periods. These changes can affect how much sunlight reaches Earth, leading to different climates.
The blue-grey color of the Blue Lias comes from a mineral called iron pyrite. This mineral is often called "fool's gold" because it looks a bit like gold.
Where did the Blue Lias form?
As you go higher up in the Blue Lias layers, the limestone and mudstone layers slowly change. They become more like a clay-rich mudstone. This change tells us something important about where these rocks formed.
It shows that these rocks were laid down in a deeper marine environment. This means the area was covered by a deeper part of the ocean when these sediments were settling.
Related pages
Images for kids
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Lytes Cary, Somerset, built of Blue Lias with Ham stone around the windows.
