Time travelling rocks at Compton Bay and Downs

Look at the different coloured cliffs in Compton Bay on the Isle of Wight. From right to left (east to west), the rocks become younger.

A couple explore the beach in the sunshine at Compton Bay
Crumbling sandy cliffs at Compton Bay with a rock-strewn beach

Explore the cliffs

The oldest orange rocks to the right were formed in rivers and lagoons. But the younger white chalk to the left was formed in a gradually deepening warm sea, formed at a time when the North Atlantic Ocean had started to widen. The types of the rock and the fossils we can find in them have come about because of this change from dry land to open sea, as the land sank and the sea level rose. This process started long ago in the Permian age 250 million years ago, and the changes happened over a very long period. The rocks we see today around Compton Bay date from 126 million years ago – in the centre of Brook Bay – to about 67 million years with the youngest chalk over Tennyson Down.

A cliff collapsse at Compton may expose new fossils

Stay safe when exploring Compton Bay

** Cliffs are unstable, rocks can fall at any time ** Don't climb the cliffs ** Don't sit too close to the base of the cliffs ** Take great care clambering over rocks, especially when wet **Do not dig in the cliff

A huge footcast, probably of an Iguanodon dating back 125 million years

125 million years old

Footcasts like this one from a giant plant-eating dinosaur have fallen out of a hard layer of siltstone in the crumbling cliffs. This area may once have been a dinosaur migration route, with herds of dinosaurs following the muddy banks of rivers, looking for plants and water. Their footprints have been filled in with silt and preserved.

125 million year old footcasts of a meat eating dinosaur at Compton

125 million years old

It's rarer to find footcasts of meat-eating dinosaurs on the beach but they’re always worth looking out for. These dinosaurs were generally smaller than the lumbering plant eaters and tended to have narrower and more pointed toes.

Two dinosaur fossils found on the Isle of Wight

125 million years old

You may be lucky enough to find a small piece of dinosaur bone on the beach. Look out for the honeycomb structure. Don’t confuse bone with lignite – lignite (which is wood that has fossilised) leaves a black mark when scraped on rock, but fossilised dinosaur bone does not.

Fossilised wood, called lignite, dating back about 125 million years

122 to 126 million years old

One of the commonest fossils found on the beach, lignite is a piece of wood that has been fossilised. It looks like impure coal and it is black, due to the way it has been mineralised. Sometimes you can see the grain of the wood in the fossil, or even impressions of the bark.

Fossilised soil on top of rocks, about 125 million years old

124 million years old

Near Hanover Point there is a layer of grey silty sandstone that has a brown crusty-looking texture on its upper surface. This top layer was once soil, and that too has now been fossilised.

The mud cracks from 120 million years ago form a remarkably regular pattern

120 million years old

These mud cracks show where a freshwater lake has dried out and then been flooded again, with silt filling in the cracks. It looks rather like modern-day crazy paving. You can find these on the underside of some of the shelly limestone slabs.

Hundreds of fossilised shells in this piece of stone found on Compton beach

120 million years old

There is a layer of limestone in which large numbers of freshwater bivalve shells called Filosina have been preserved. The layer can be quite thin, and the fragments look like uneven, discarded paving slabs.

120 million year old oyster shells found at Compton Bay

119 million years old

These large fossil oyster shells have come from a band of grey and green clay and sand. They show that the environment has become marine, as opposed to the fresh water deposits that gave rise to the dinosaur and wood remains.

An ammonite, dating from 93-98 million years ago

93 to 98 million years old

This fossil fragment of an ammonite lies in the Grey Chalk, which is older than the White Chalk, but it would have been part of the same warm tropical sea.

A bi-valved shell and 10 million years younger cockle-like shell on the right

93 to 98 million years old

The fossil on the left is the same age as the ammonite, but this was a bi-valved shell. The one on the right is like a large fossilised cockle shell, but comes from the White Chalk layer which means it is younger, by about 10 million years.

An 86 million year old sea urchin found at Compton Bay

86 to 88 million years old

This fossilised sea urchin has been preserved in flint. When it was alive it would have scavenged for food on the sea floor. It has now fallen from the chalk cliffs, preserved for all time as a fossil.

A 65 million years old sponge

67 to 93 million years old

This isn't a shell but a flint that has fallen from the chalk cliffs, and it was originally a sponge. Most flint is the fossilised remains of sponges that grew on the floor of the tropical sea. Some flints, like this one, show the actual shapes of their original sponges.

An 8000 year old piecce of semi-fossilised wood sticks out of the Compton Bay cliff

8,000 years old

The layers of gravel at the top of Compton cliffs were deposited by a river that meandered its way towards Freshwater Bay. Occasionally, pieces of semi-fossilised wood can be seen. They would have fallen into the riverbed at the same time.

Four hazelnuts, almost 10000 years old, found at Compton Bay

8,000 years old

These semi-fossilised hazelnuts (known locally as “Noah’s nuts”) came from the same layer of gravel as the semi-fossilised wood. They too would have been dropped into the river at the same sort of time. You can sometimes find them on the beach near the steps at Hanover Point.

A rusting wreck from 70 years ago in Compton Bay

70 years old

The tug, Carbon, was being towed from Portland to Southampton for salvage when the towing line broke whilst off the Needles in 1947. The ship drifted into Compton Bay and went aground on the rocks. It was decided it wasn't worth recovering her and so she has remained a familiar landmark, slowly rusting away so each year there is less to see.

Part of the National Trust car park above Compton Bay has broken away towards the sea

1-10 years old

Atlantic storms sweeping into the English Channel mean that the south-west coastline of the Isle of Wight is eroding fast. Car parks and roads will not stop this natural process – our car park at Hanover Point loses parking bays at regular intervals. Along the beach at Compton you may find parts of the car park surface, which sometimes get mistaken for rare dinosaur bones.

The tide comes in on the Compton Bay Sandcastle Competition 2015

0-1 year old

We organise an annual sandcastle competition here in the summer. This is a great opportunity for family and friends to work together and a chance to exercise your construction and creative skills. By the next tide, the sea has wiped them away.

Rubbish mostly dumped at sea ends up on Compton beach

0-1 month old

Lots of rubbish, usually plastic of some sort, ends up on the beach at Compton Bay. Some is left by visitors, but most is swept ashore, having been dumped at sea. As well as being unsightly, it can be dangerous, so we need regular beach clean-ups. The surfers help us keep the beach clean.

A very recent beach find at Compton Bay, a whelk's egg case

Since last high tide

Whelk egg cases are commonly found on the beach, washed up by tides. Each case may originally have held over 1,000 eggs, but only a few would have hatched, with the others providing food for the small hatchlings.