Geology

Topsoil

The dark band of soil at the very top of the cliffs, in which the vegetation grows. These soils have been created in the last 10,000 years since the last Ice Age.

Ice Age Sediments

These are the thick yellow and brown sandy deposits of the upper half of the cliffs, known as the Contorted Drift. If you look at them carefully, you will see very fine layering of different types of sediments. Some were made by the streams, created when the glaciers melted, others from wind blown sands during intensely dry and cold periods.

Sometimes the fine layers are twisted into strange patterns, this is where the weight of the huge ice sheets above pushed and contorted the deposits. These are the best Ice Age sediments to be seen in the whole of the UK, and better than most found in Europe! Students from various Universities visit West Runton each year on field trips to study them. These layers do not contain any fossils. Temperatures during the cold phases of the Ice Ages were so low that nothing could live here!

Some of the larger stones in these sediments have been transported all the way from Northern England, Scotland and Norway. They were incorporated into the ice sheets that were up to half a kilometre thick and hundreds of miles long! moving south only a few metres a year. Most of the geology we have in Norfolk relates to only sedimentary rocks, deposits laid down by rivers, seas and glaciers.

However, the individual rocks transported to West Runton from far away by glaciers are usually quite different from the other rocks we see in the cliffs and on the beach. They are known as “erratics”. They are usually “igneous” or “metamorphic” rocks that have been created or transformed deep in the Earth, through great heat and pressure. They are very different from the flints that make up most of the material on the beach. See if you can find some!

Upper Cromer Forest Bed

Silts and sands deposited in marine and estuary conditions. Some marine shells can be found in these deposits.

West Runton Freshwater Bed

The hard black deposit, four to six feet thick at the base of the cliffs. This particular section of the most extensive “ Cromer Forest Bed” series of deposits, is the internationally famous “ Type Site” for the “Cromerian Interglacial Period”.

People studying other sites around Europe of a similar age use this deposit as a benchmark to determine whether their sites are older or younger. This deposit was created by a slow moving river running through a grassy and wooded landscape about 650,000 to 720,000 years ago created this deposit. There were no cliffs here at this time. England was connected to Europe, and the North Sea was much further north.

Apart from elephants and Rhinos etc., it would have looked similar to the Norfolk Broads today. This ancient riverbed is the best source of Pleistocene fossils in the British Isles. The Pleistocene Period lasted from 1.6 million years ago to just 10,000 years ago. If you look very closely at this deposit you can see twigs sticking out of the dark sediment. Pine cones, fungi, wood and seeds have also been found.

Easily visible are the remains of thousands of freshwater molluscs such as snails and oysters. It was in this deposit that the world famous West Runton Mammoth was found. This 85% complete, 4.5metre high skeleton, is the largest mammoth skeleton ever found in the world ( it is much bigger than most dinosaurs) it is also the best example of its species in the world! Mammuthus Trogontherii, now sadly extinct.

Other fossil animal remains found in this deposit include, various mouse, vole and deer species, spotted hyena, horse, duck, goose, wolf, wild boar, bear and extinct species of rhino, giant deer, giant beaver, big cat and macaque monkey. Some of these animals might sound quite exotic but the climate back then, before the Ice Ages, was almost exactly the same as today. Some of these species are no longer with us in the UK because they did not survive the difficult climatic conditions of the Ice Ages, and some were hunted to extinction by our ancestors.

This part of the cliffs is a Site of Special Scientific Interest (SSSI) and is protected by law. Please do not dig into this deposit. Large bones are very rare. It is best to get down on your hands and knees and search the surface and sides of the deposit very carefully for smaller specimens, which are more common.

The Weybourne Crag

These concreted, orange, iron rich sands, gravels and pebble deposits containing clays date to between 1.5 and 3 million years ago. They represent an environment that was a cool sea very close to coastal cliffs. In these layers you can find sea shells and occasionally the remains of dolphins and whales.

Interestingly you can also find the remains of voles, shrews, beaver, deer, rhino, horse and elephants. As this seabed was close to a coast, the remains of these land animals were probably washed out to sea by nearby rivers. Between this layer and the sediments below, there is a gap of about 87 million years! This gap was created when the sea was eroding, rather than depositing sediments sometime around 3 and 4 million years ago.

The Chalk

The oldest material to be seen at West Runton is the white chalk platform of the lower beach observable during low tide, usually obscured by loose beach material such as sand, flints and pebbles. This chalk deposit was created about 90 million years ago as the countless millions of skeletons of tiny marine animals sank to the floor of a warm, shallow tropical sea and built up thick deposits.

Over millions of years this material turned into the chalk we are familiar with today, which stretches from Norfolk all the way to the South Downs and the Isle of Wight. All the flints that you see on the beach have come from the chalk. These flint stones, naturally occurring in vast numbers in the chalk, are made from the silica ( a mineral ) of sponges that used to live on the sea floor at the time of the ancient warm seas. You can sometimes find the remains of these sponges and corals within the flints, especially the hollow ones.

You can also find the remains of echinoids or “sea urchins”. These are round, fist sized fossils that look a bit like the red sea anemones you can see living on the rocks of the beach today. They are related to star fish and have a five fold symmetry. You can also find “belemnites”, long carrot like fossils the size of small fingers. These were once the long hard shells of creatures related to the squid and octopuses that live in warm seas today.

If you do find anything interesting and want to know what it is, Cromer Museum offer an identification service. Martin Warren ( former curator Cromer Museum ) runs several guided Geology Walks from the car-park. Dates and times of these walks can be found on his website http://www.northfolk.org.uk