Brighton to Newhaven Cliffs facts for kids
| Site of Special Scientific Interest | |
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| Area of Search | East Sussex |
|---|---|
| Interest | Biological Geological |
| Area | 165.4 hectares (409 acres) |
| Notification | 1986 |
| Location map | Magic Map |
The Brighton to Newhaven Cliffs are a very important natural area in East Sussex, England. This special place stretches along the coast between the towns of Brighton and Newhaven. It covers about 165.4 hectares (which is about 408 acres). It's recognized as a Site of Special Scientific Interest because of its amazing plants, animals, and unique geology. Part of this area, about 16.4 hectares, is also known as the Castle Hill, Newhaven Local Nature Reserve.
Contents
Geology: A Window into Earth's Past
The cliffs between Brighton and Newhaven are like a giant history book made of rock. They show us some of the best and biggest examples of ancient layers of rock in England. These layers are super important for understanding Earth's past.
Ancient Fossils and Rock Layers
The way the rocks are gently folded and how easy it is to see them in the cliffs makes this a great spot to find fossils. These fossils come from a time called the Upper Cretaceous period, specifically from the Santonian and Campanian ages. Scientists use these cliffs as a key place to study this ancient time.
Black Rock: A Story of Ice Ages
Black Rock, near Brighton, is a very important spot for studying Earth's recent history, especially the Quaternary period. Scientists have been interested in it for over 150 years! At Black Rock, the modern sea cliff cuts across an older, "fossil" cliff and a flat area called an "abrasion platform."
This old platform is covered by layers of sand and shingle (small stones) that were once a beach. These are called "raised beach deposits" because they are now higher than the current sea level. Inside these deposits, scientists have found pieces of shells. By studying these shells, they've figured out that this old beach and cliff formed during the second half of the last interglacial period. This was a warmer time between two ice ages.
Evidence of Past Climates
The space between the old beach and the ancient cliff is filled with lots of coarse chalk rubble. This rubble probably came from the old cliff breaking down during the Devensian period, which was the last major ice age. You can also find chalk muds and fine chalk gravel here. These might be fan-shaped deposits that flowed down the cliff.
These muds also contain a lot of loess, which is a type of fine, wind-blown silt. On top of these layers are even coarser deposits formed by a process called solifluction. This is when soil and rock slowly flow downhill, especially when the ground is frozen and then thaws.
What makes these chalk rubble and solifluction deposits really special are the fossils they contain. Scientists have found remains of many large mammals from the Devensian Ice Age. These include amazing creatures like the Woolly mammoth (Elephas primigenius), an ancient rhinoceros (Tichorhinus antiquitatus), and even ancient horses (Equus caballus).
Understanding Sea Levels and Glaciations
The landforms, rock layers (stratigraphy), and mammal fossils at Black Rock give us a super valuable record. They help us understand how sea levels have changed over time. They also show us how environmental conditions changed during the last few glaciations (cold periods) that affected this area. It's interesting to know that Southern England, unlike much of the rest of the UK, was not covered by huge glaciers during these ice ages.
Faults and Folds in the Chalk
At Saltdean, another part of the cliff, you can see a fantastic example of "normal faults" in the chalk. A fault is a crack in the Earth's crust where the rocks on either side have moved. These faults look like they run in a north-northeasterly direction.
These chalk cliffs are on the southern side of the Weald anticline. An anticline is a large upward bend or fold in layers of rock. It's the main geological feature of south-eastern England. These faults likely formed when the Earth's crust was stretched during a time of great pressure in the mid-Tertiary period. The formation of the Weald anticline is actually linked to the creation of the huge Alpine mountain range to the South!
Frost Patterns in the Cliffs
Along much of the cliffs between Brighton and Newhaven, you can see interesting patterns in the top meter of the chalk. These are called "frost involution structures." They look like repeated "U" shapes or wavy patterns. They formed during the Devensian (last glacial period) when the ground repeatedly froze and thawed.
When the ground froze, it pushed up the chalk layers, turning small pieces more upright. Then, present-day soil covered them. The middle of these "U" shapes is often filled with finer chalk and sand, which looks more orange or yellow. If you remove the grass and soil, you can see that these structures form a polygonal (many-sided) pattern on the surface. The slope of the land seems to affect how they form. On steeper slopes (more than 20 degrees), a process called solifluction was more common. This prevented these "U" shapes from forming. This is similar to how patterned ground features, like stone nets, can become stretched out on slopes, forming "stone stripes," which you can see in cold environments today or in places like Dartmoor where they formed long ago.
Undercliff Walk: A Path by the Sea
The Undercliff Walk is a popular path that runs for about 4.5 kilometers (2.8 miles) at the bottom of the cliffs. It goes from Black Rock in Brighton all the way to Saltdean. When it's open, this path along the seafront is a favorite spot for people who enjoy walking and cycling.
However, the path sometimes has to close. This happens when rocks fall from the cliffs, especially during stormy winters like in 2000/01, 2012/13, and 2020/21. To help keep people safe and prevent rocks from falling onto the path, special netting and other devices have been put on parts of the cliffs that are known to be unstable.
