Downland facts for kids
Downland, also called chalkland or chalk downs, describes special areas of open, rolling hills. These hills are made of a soft, white rock called chalk. You can find these unique landscapes mainly in southern England. The word "downs" comes from an old English word, "dun," which simply means "hill."
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Where Are Downlands Found?
The biggest area of downland in southern England is Salisbury Plain in Wiltshire. From there, these chalky hills stretch in different directions:
- Southwest: They go through Cranborne Chase into Dorset (called the Dorset Downs) and south through Hampshire (the Hampshire Downs) all the way to the Isle of Wight.
- Northeast: They continue along the Berkshire Downs and Chiltern Hills. These cover parts of Berkshire, Oxfordshire, Buckinghamshire, Hertfordshire, Bedfordshire, and even into Cambridgeshire.
- East: You'll find downlands north of the Weald in Surrey, Kent, and parts of Greater London. These are known as the North Downs.
- Southeast: The downlands extend into West Sussex and East Sussex, forming the famous South Downs.
Similar chalk hills exist further north in England, in Lincolnshire and Yorkshire. There, they are called the Wolds.
How Downlands Formed: Geology Basics
Downlands are made mostly of a rock called the Chalk Group. This rock formed a very long time ago, during the Upper Cretaceous period. It's a type of limestone that is usually soft, white, and full of tiny holes.
What is Chalk Made Of?
Chalk is mostly made of tiny bits of ancient sea creatures. These include microscopic coccoliths and other small fossil pieces, all mixed in a fine mud. Sometimes, small amounts of a material called silica were also laid down. This silica came from tiny sponge spicules. Over time, this silica moved around and formed hard lumps called flints within the chalk.
How the Land Changed Over Time
After the chalk was formed, the land in southern England was pushed up, cracked, and bent. This happened because of huge forces from far away, like the Alpine Orogeny (a period when mountains like the Alps were forming).
- Cracks and Water: The cracking made the chalk very porous, meaning water can easily flow through it. This makes chalk a major aquifer, which is like a natural underground water storage.
- Hills and Valleys: Over millions of years, the land kept changing. Some areas were pushed up, forming structures like the Wealden Anticline. Later, erosion (wearing away by wind and water) created the rolling hills and valleys we see today.
- Ice Age Effects: During the last ice age, the area was near the edge of giant ice sheets. This caused more changes, like the chalk dissolving and existing valleys being reshaped by frozen ground and melting snow.
The Shape of Downland Hills
Downland landscapes appear when the chalk rock becomes visible at the surface. The chalk slowly wears away, creating the familiar rolling hills and valleys.
- Steep and Gentle Slopes: The chalk layer in southern England is often tilted. This means chalk downland hills usually have one very steep side, called a scarp slope. The other side, called the dip slope, is much gentler.
- White Cliffs: Where these chalk downs meet the sea, they form dramatic white cliffs. Famous examples include the White Cliffs of Dover and Beachy Head.
Water in the Downs
Chalk is very good at soaking up water. So, the level of underground water (the water table) in chalk hills goes up in winter and down in summer. This creates some special features:
- Dry Valleys: Many valleys in downland areas are often dry, especially in summer. These are sometimes called coombes.
- Winterbournes: Some streams only flow during the wetter winter months. These are known as winterbournes. Taking too much water from the underground chalk can put stress on these unique streams.
- Springlines: In the valleys below the downs, at the bottom of the chalk layer, you might find other types of rock like greensand or gault clay. Water often comes out of the ground where the chalk meets these other layers. This is called a springline. Many old villages and farms were built along these lines because it was the only place to find water on the higher land. A great example is below the scarp of the White Horse Hills.
- Dewponds: Since there's often no surface water on the higher downs, people sometimes built artificial ponds called dewponds to collect water for animals.
Downland Soil
The soil on chalk downland in England is usually thin and lies directly over the chalk rock. This special soil is called rendzina.
- Simple Layers: Unlike many soils with clear layers, a chalk rendzina soil has only a shallow, dark top layer rich in humus (decayed plant matter). Below this, it gradually changes to a lighter brown soil with small chalk pieces, and then to the white chalk itself. This is because chalk is almost pure calcium carbonate, and doesn't have much of the clay minerals that help build deeper soils.
- Sheep Tracks: On steep chalk downland slopes, you might see a ribbed pattern of grassy, horizontal steps. These steps are about a foot or two high. While animals like cattle and sheep walking along them have made them more obvious, these "terracettes" (often called sheep tracks) were actually formed by the slow downhill movement of soil, a process called soil creep.
Downland Habitats
The main type of habitat on chalk downland is called calcareous grassland. This grassland is kept short by animals grazing on it, both farm animals and wild ones.
- Why It's Special: Chalk downland is often not good for intense farming or building because the soil is shallow, doesn't have many nutrients, and the slopes are steep. Because of this, many downland areas were left untouched when other land was ploughed. This shallow soil makes downland ecosystems very delicate and easy to damage.
- Threats: Today, with modern farming tools and fertilizers, some downland that was once wild is now farmed. Also, if there aren't enough animals grazing, many downland areas can turn into scrub (bushes and small trees). This destroys the special calcareous grassland.
- Decline and Protection: The amount of lowland calcareous grassland in the UK has shrunk a lot since the mid-1900s. For example, in Dorset, over half of it was lost between the 1950s and early 1990s. To protect its unique biodiversity (the variety of living things), much of the remaining chalk downland is now protected.
