Cave GeoPaleo

• Discover the Caves' Archaeological Importance
• Discover the Caves' Geological Importance

Discover the Caves' Archaeological Importance

Here you will find details of the Progression of Man, and the Animals who used the caves.

Ancient Britons in the Caves

Evolution of British Man

Progression of man in Kents Cavern

The progression of man across the continents is thought to have taken place during the cold periods. During the warm periods melting ice caused the sea level to rise and oceans separated the continents. Furthermore during warm periods food would have been easier to find. On the edge of the glacial areas the vegetation was grassland or tundra. Tundra is a cold, treeless area and characterised by very low temperatures, little rain or snow, a short growing season, few nutrients, and low biological diversity. The word tundra comes from the Finnish word tunturia, which means "treeless plain." The area around the caves during the three ice ages would have been tundra. Homo Erectus The history of man in Britain goes back to the Lower Palaeolithic period, the Stone Age, when homo erectus, the first hominid to migrate and survive outside the African continent, dispersed into Asia and to the edge of Europe about 700,000 years ago. The first of the Stone Age tool makers was Australopithecus afarensis, an ancestor of homo erectus who lived in Africa. The best known fossils from austalopithecus were found in Ethiopia and named 'Lucy'. Kents Cavern is the oldest recognisable human dwelling in Britain and has some of the oldest evidence of man's occupation of Britain. Five hand axes, made from flint, found in the caves are currently dated at 450,000 years old. Found in the breccia along the Long Arcade and Clinnicks Gallery, deep in the cave, hand axes were made and used by European Homo erectus, also known as Heidelberg man nearly half a million years ago. Heidelberg Man Heidelberg man was named after workers in a gravel pit discovered a jaw bone near Heidelberg in Germany. The find consisted of a lower jaw with a receding chin and all its teeth. While the jaw appears to be homo erectus, the teeth are smaller than other erectus finds. The remains are estimated to be about 500,000 years old. Evidence of heidleberg man in Kents Cavern comes from large flints worked into hand axes nearly half million years ago. Neandertal The first Neandertal remains were found in the Neander valley in Germany in 1856. These bones were found to be different from modern humans. Neandertals lived during the middle and upper palaeolithic period between 120,000 and 10,000 years ago. The tools they made are very distinctive and changed very little during this time. Recent Neandertal artefacts from the end of the last ice age (10,000 years ago) demonstrate workmanship associated with modern man, homo sapiens, indicating that the two species lived side by side. The relationship between Neandertals and homo sapiens, ourselves, what language and social capabilities they had and what caused them to become extinct is still a much debated issue. Kents Cavern is rich in Neandertal flint implements indicating that this species was well established this far north in Europe. Homo Sapiens The upper palaeolithic period is associated with the evolution of modern man, homo sapiens. The first discoveries in Europe are about 40,000 years ago and a jaw bone with teeth found in the Vestibule Chamber in Kents Cavern, close to the entrances used today, is 31,000 years old. Mesolithic The ice age is over and the climate of Britain is pretty much the same as today. Stone implements are attached to wooden shafts to form arrows and spears. Bones and shells were shaped into tools. Mesolithic material is found in Kents Cavern. Neolithic Neolithic (new stone age) period begins with the first evidence of farming. Stone axes, antler combs and pottery are in common use. Flint is still the main source of sharp cutting edges. Bronze Age Copper was the first metal used by man. It could be worked into shapes by pouring the molten metal into prepared moulds. When tin was combined with copper, a much better material was formed, Bronze. Throughout the bronze age, trade began to develop and man began to acquire specialised skills. Pottery, copper casting, wood working, animal husbandry all became recognisable skills. Farms and settlements such as the Bronze Age site at Grimspound on Dartmoor became established. Iron Age Forging copper into tools, weapons and ornaments soon led to the development of the necessary skills to smelt iron ore into the much stronger metal, Iron. Iron Age artefacts are numerous and include cauldrons, buckets, helmets, shields and pins and broaches. The increasing trade links with other parts of Europe created the need for defence and Iron Age forts. Defendable homesteads such as the ones at Walls Hill, Torquay and Berry Head Brixham are good examples from this period. Roman Britain In 55BC, Julius Caesar first sends troups to Britain, but they are forced to retreat. First actual invasion was in 43AD.

Animals in the Caves

Dinosaurs have been extinct for about 65 million years. The oldest remains of animals found in Kents Cavern are cave bear about 500,000 years old. This period is the lower palaeolithic period, the Old Stone Age. Man has begun to move north into Europe from Africa. At the same time, half a million years ago, these early bipedal hominids, walking on two legs, reached this part of Britain. Ancestral Cave Bear (Ursus deningeri) 700,000 - 10,000 ya Shoulder Height 1.5m Length 2.7m Weight 250-350kg This bear has been known about from 700,000 years ago and evolved into Ursus spelaeus some 300,000 years ago. In Kents Cavern remains of Ursus deningeri were found in the breccia and have been dated as old as 500,000 years. They were mainly vegetarian and used the caves to hibernate, entering the caves in autumn. It was not uncommon for these bears to die during hibernation, possibly as a result of excessive exposure to water during hibernation lowering the body temperature below the optimum level. Over the centuries this resulted in many hundreds of bones and teeth being found in the caves. Visitors today see a cave bear skull still embedded in the cave wall in the Water Gallery. The complete skull of a female bear found in January 1948 and dated at 420,000 years old is also on display. Cave Bear (Ursus spelaeus) 300,000 - 10,000 ya Shoulder Height 1.5m Length 2.7m Weight 330-440kg In Kents Cavern a few specimens have been identified from about 50,000 to 20,000 years ago. This bear was much larger than the ancestral cave bear being about twice the body weight of brown bears in Europe today. The relative rarity of this cave bear in Britain in the last ice age shows that although the species still occasionally ranged this far north, it had largely lost its foothold here probably as result of the invasion of the brown bear. Cave Lion (Panthera leo) 500,000 - 20,000 ya Shoulder Height 1.4m Length 2.5m Weight 250-400kg This lion was larger than its relatives in Africa today but otherwise quite similar and is not regarded as a separate species despite the common name "cave lion". Cave lion bones found in Kents Cavern were found in the main cave earth and are from the middle of the last ice age between 50,000 - 20,000 years ago. Sabre Tooth Cat (Homotherium ladidens) 3million - 200,000 ya Shoulder Height 1m Length 1.7m Weight 80-130kg The discovery of sabre-toothed cats in Britain caused a sensation in the last century when they were first described by Sir Richard Owen from Kents Cavern (he called them Machairodus). Though rare, they are now known to have lived in Europe from about 3 million years ago until their extinction, perhaps 200,000 years ago, although there are occasional claims for much later persistence. In Kents Cavern about half a dozen canines have been found in the breccia, believed to be around 400,000 years but none have been found from later periods. The sabre-toothed cat was about the size of a present-day lion but with elongated fangs and front legs with a short tail and a somewhat sloping back appearance. Mammoth (Mammuthus primigenius) 135,000 - 11,000 ya Shoulder Height 3 m An ice age animal whose name mammoth is thought to come from the Russian word "mammut" meaning "earth mole" as they believed the animals to live underground and die on contact with the light, explaining why they were always found dead and half-buried. Complete remains of mammoths have been found in Siberia. In Kents Cavern mammoth remains include teeth and leg bones likely to have been dragged into the caves by scavenging hyaenas. Mammoths became extinct at the end of the last ice age although one theory on mammoth extinction is that they were exposed to viruses and diseases carried by dogs. Dogs were being used increasingly by man to hunt the beasts. Cave Hyaena (Crocuta crocuta) 500,000 - 20,000 ya Shoulder Height 1m Length 1.7m Weight 80-130kg The hyaenas of the last cold stage such as those from Kents Cavern were markedly larger than those living in Africa today. However, they were otherwise very similar, and are not now regarded as a separate species, despite the common name "cave hyaena". As well as their bones and teeth, fossil droppings (coprolites) are also found. Analysis of pollen contained in these droppings give clues to the flora (plants) that grew outside the cave at the time. Many of the bones of other animals found in the caves are scratched by gnaw marks from the hyaena. Hyaena not only scavenged but hunted in packs of 10 to 25 animals, mostly at night. Their diet consisted of deer, horse, bison, baby mammoth and woolly rhino. These animals made dens in caves where they lived with their young. Other Animals from the Caves Wolf (Canis lupus) Red Fox (Vulpes vulpes) Woolly Rhino (Coelodonta antiquitatis)

Discover the caves' Geological Importance

Below is a table showing the Timeline for Planet Earth. Please Click on the names of the periods to link to more information on the era. On this page you will find details of the Creation of the Earth as we know it, Ice Age of Britain and the Geology of Kents Cavern.

History of our Planet

Precambrian 4600 - 570 million years ago

4600 million years ago planet earth is a glowing molten cauldron of gases. During the Pre-Cambrian period, the moon appears 4,500ma, a continental crusts takes shape by 3,000 ma. The oldest rocks in Britain are 3,300ma found in Scotland. Oxygen builds up and the ozone shield protecting the planet from solar radiation is forming 2,000ma. The pre-Cambrian ends with the planets first major ice age 700 ma and the appearance of bacteria and fungi on the planet.

Paleozoic 570 - 245 million years ago

570ma Scotland was part of the North American continent and close to the equator. England was much further south and colder. The first forms of life appear on the planet as marine invertebrates, including trilobites. Sea levels and temperatures are rising. The first vertebrates, animals with backbones, appear as fish by 490ma. Over 360ma most of Britain is covered by a shallow tropical sea containing coral reefs and other marine creatures. The Devonian limestone, which today surrounds Kents Cavern, is being formed by these first forms of life. By 260ma the continents are being jammed together into one large land area called Pangea allowing plants and reptiles, evolved from the fish, to migrate across the continent. Britain became a desert. The end of this period is marked by a mass extinction destroying over 96 percent of the earth's marine life and three quarters of land animals.

Mesozoic 245 - 65 million years ago

The Mesozoic is the age of the dinosaurs. Pangea begins to break up into separate continents creating shallow marine habitats for species to evolve. Much of Britain is covered by sea so dinosaur fossils are rare although sea life fossils can be found from this period. But the period ends abruptly 65ma with the mass extinction of all dinosaurs and three quarters of all other species. Scientists believe this to have been caused by a massive collision with an asteroid.

Tertiary 65 - 1.6 million years ago

During this period plants, insects and mammals dominate the planet. The continents as we know them today are formed. During this period the north Atlantic is widening with volcanic activity off the west coast of Scotland. The Alps are formed as Africa collides with Europe. At the end of the Tertiary 2ma, underground rivers are forming the passages and chambers in Kents Cavern.

Quaternary 1.6 million - 12,000 years ago

During this period bipedal hominids, men walking on two legs, are evolving and moving out from the African continent. Britain is being subjected to successive ice ages and warmer interglacial periods. Homo erectus is moving into Europe and by 500,000 years ago, Homo heidelberg is using the caves at Kents Cavern as shelter. Neandertal man lived in Europe about 200,000 years ago. Many flint tools from Neandertals are found in Kents Cavern. Homo sapiens is in Europe about 40,000 years ago and jaw bones found in Kents Cavern show modern man was using the caves 31,000 years ago.

Ice Age Britain

The passages and caves in Kents Cavern were created about 2 million years ago by water carving its way through the 385 million year old limestone. The period from about 1.6million years ago to 12,000 years ago is called the Quaternary. During this period there were warm and cold periods. The most important ice ages (cold) and interglacial (warm) periods when ice covered Britain are listed below. The ice fields never came as far South as Kents Cavern stopping in Somerset. Night-time temperatures were about -10°C and day time temperatures were about +10°C during the cold periods. YEARS AGO NAME OF PERIOD CLIMATE 750,000 - 350,000 Cromerian Interglacial Warm 350,000 - 250,000 Anglian Glacial Cold 250,000 - 200,000 Hoxnian Interglacial Warm 200,000 - 125,000 Wolstonian Glacial Cold 125,000 - 72,000 Ipswichian Interglacial Warm 72,000 - 12,000 Devensian Glacial Cold During the cold stages, the sea levels would be much lower than today, up to 120metres lower during a glacial maximum. At very low tides in Torbay fossilised tree trunks can be seen, the remains of a now submerged forest giving evidence of lower sea levels. When the sea levels were lower, animals and early man could freely walk from France to England. As the planet's temperature rose during the interglacial period, the sea level would rise again as the ice fields melted, closing off the links to the continent. Plant life would grow abundantly around the cave and warm weather animals, particularly hippopotamus would be found in Devon. Each successive ice age left its mark on Kents Cavern by infilling the caves with secondary limestone deposits and sediment brought in by the flowing underground river. Today there is no underground river in the caves. Ice never covered Kents Cavern, neither did it cover any of Devon and Cornwall. Significant calcite formations, stalagmites and stalactites, in the caves only really occurred during the interglacial periods when the climate was warm. Plant life was plentiful on the surface generating the necessary levels of carbon dioxide in the atmosphere to give the carbonic acid the right strength to dissolve limestone rock and deposit calcite formations in the caves. During each warm period a new stalagmite floor would be created in the caves, entombing bones and artefacts from previous times under the stalagmite floor. There they would remain until the 19th century when the first excavations of Kents Cavern began, first by Father John MacEnery in the 1820s and then later by William Pengelly, 1865 to 1880. It was William Pengelly who carried out the most extensive and well documented studies of the caves.

Geology of Kents Cavern

Devonian Limestone

The rock surrounding Kents Cavern is Devonian Limestone, a sedimentary rock composed principally of Calcium Carbonate (CaCO3). In Kents Cavern the limestone is primarily white but coloured by the minerals in the rock above. High levels of Iron Oxide give much of the cave a reddish brown colouring, similar to the South Devon soil. Limestone is formed in one of two ways, either with the assistance of living organisms or by direct crystallisation. Living Organisms 400 million years ago, this part of Southern England lay beneath the sea. The seas were home to organisms with shell and bone structures. These are the earliest forms of life on this planet, who extract calcium carbonate from seawater to make their shells and bones. Mussels, oysters, limpets, winkles , whelks and coral are all organisms doing the same today. When these organisms die, their shells and bones settle on the sea bed and accumulate. Wave action breaks up the shells into small pieces and over time, millions of years, these fragments harden into limestone. The Kents Cavern limestone is hard. Chalk is another form of calcium carbonate, but soft and formed from the shells of microscopic animals. Direct Crystallisation The other way limestone is formed is by direct crystallisation of water, usually seawater. If water containing calcium carbonate is evaporated, the calcium carbonate is left as crystals. Today this process is active in Kents Cavern. Rain water (H2O) mixes with carbon dioxide (CO2) in the air to form a weak carbonic acid (H2CO3). More carbon dioxide (CO2) is absorbed when the water (H2O) percolates through the soil, especially if the soil is rich in organic matter. This weak carbonic acid (H2CO3) seeps down through the limestone (CaCO3). As it does so it dissolves Limestone and forms a calcium bicarbonate (Ca (HCO3)2) solution.The fissures (holes) through which this solution flows get larger and after time passages are formed allowing the water to flow faster and bring in silt and sediment. This helps to wear away the surfaces of the passages and eventually pebbles, rocks and boulders are washed through passages carving ever-larger passages through the limestone. The caves are forming. As this process creates larger caverns, the caverns become air-filled. This will also happen when the water table drops because of falling sea levels during cold ice age periods. The water can now enter the roof of the caverns and does so as a calcium bicarbonate solution. The carbon dioxide content from this solution is released to the air, leaving behind the calcium carbonate in the form of calcite. The result is calcium carbonate being re-formed into a variety of Calcite formations, the most commonly known being stalagmite and stalactites we see in the caves today. The humidity and temperature of the cave environment and the rate of in-flow and the chemical content of the water are the main factors controlling the rate of calcium deposition.

Breccia

Breccia is another sedimentary rock that forms by cementing rock fragments, the size of cobbles and pebbles. The rock fragments are brought into the caves by water. The wave movement sifts the rocks into even sizes. The cementing agent is calcite and this fills the spaces to form a solid rock. Breccia is a cold climate material when fragments are brought down from the hill above as a result of a freezing and thawing situation. Artefacts and bones found in breccia are particular difficult to date because the surrounding material can be from many periods. Surface material is bought into the caves during a cold period. As the climate changes, a stable soil develops on the surface, limiting the number of rock fragments entering the caves. The flow of water is then smoother and this encourages the growth of calcite.

Calcite Formations

Water seeps through the limestone and appears as a drop of water hanging from the roof. The carbon dioxide (CO2) content in the water solution is released into the cave atmosphere leaving a tiny ring of calcite around the water drop. Eventually the water drop falls to the cavern floor and is replaced by another drop on the ceiling. The process is repeated time after time and slowly the calcite deposit grows. Good calcite formation occurs when the climate is warm, when plant growth on the surface is producing sufficient carbon dioxide to dissolve the limestone. During the ice ages calcite formation is limited. The life cycle of a stalactite formation starts when a straw is formed. This grows into a stalactite, which can either be a conical shape or a curtain shape or can have an irregular crystallised shape called a helictite. Exactly the same happens when the water drop hits the floor of the cave where stalagmites are formed. Water flowing down the side walls of the cave will leave a calcite deposits called flowstone looking like a frozen water fall. It takes about 1,000 years to grow 1 to 2 cm of calcite in Kents Cavern. After time stalactites and stalagmites will join and form a column. Examples of all these formations can be seen in Kents Cavern. Straws These very fragile cylindrical straw formations are formed on the ceiling as water seeps out of the limestone roof of the cave. As the water drop hangs on the roof, the carbon dioxide (CO2) content is released into the cave air leaving a tiny ring of calcite around the water drop. Eventually the water drop falls to the cavern floor and replaced by another on the ceiling. The process is repeated time after time and the straw takes shape. The uniform size of the water droplet gives the straw its almost constant diameter. Click here for picture Stalactite If the water runs down the outside of a straw, a thicker layer of calcite will build up as more carbon dioxide (CO2) is lost to the atmosphere of the cave. Eventually a cone shape will begin to form called a stalactite. These always hang from the ceiling and hold "tight" to the ceiling. Note that stalactite is spelt with a "c" for ceiling. Click here for picture Curtain or Shark's Fin When the water runs down a sloping surface the resulting calcite deposit forms a hanging curtain which takes the form of shark's fins. These curtain stalactites often contain lines of colour from the differing mineral content of the water solution. Click here for picture Helictites A rare and beautiful formation that seems to defy gravity is the helictite. The calcite crystal growth is in all directions twisting and curving, sideways and upwards. Click here for picture Stalagmites As the water falls from the ceiling a layer of calcite will build up on the floor, as more carbon dioxide (CO2) is lost to the atmosphere of the cave. When the drop rate is slow, (one drop every hour say) a straight upright candle shape will form and where the rate is fast (one drop every second say) then the formation will be more like a beehive. Stalagmites grow up from the ground and "might" reach the ceiling. Note that stalagmite is spelt with a "g" for ground. Click here for picture Columns After time, stalactites and stalagmites will join together to form columns. The water will then continue to run down the outside and the calcite deposit will thicken the column. Click here for picture Flowstone Flowstone is a beautiful formation that looks like a frozen waterfall. As water flows down the walls of the cave, the calcite deposit is spread over a large area creating a dripping candle effect. Many of the cave walls in Kents Cavern have flowstone deposits. Click here for picture