Bourne SSSI, Avon is a 8.47 hectare

Hectare

The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...

 geological Site of Special Scientific Interest near the village of Burrington

Burrington, Somerset

Burrington is a small village and civil parish in Somerset, England. It is situated in the Unitary authority of North Somerset, north east of Axbridge and about east of Weston-super-Mare...

, North Somerset

North Somerset

North Somerset is a unitary authority in England. Its area covers part of the ceremonial county of Somerset but it is administered independently of the non-metropolitan county. Its administrative headquarters is in the town hall in Weston-super-Mare....

, notified in 1992.

This site is of considerable importance because it has provided detailed information upon the composition of a north Mendip

Mendip Hills

The Mendip Hills is a range of limestone hills to the south of Bristol and Bath in Somerset, England. Running east to west between Weston-super-Mare and Frome, the hills overlook the Somerset Levels to the south and the Avon Valley to the north...

 Pleistocene

Pleistocene

The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 alluvial fan

Alluvial fan

An alluvial fan is a fan-shaped deposit formed where a fast flowing stream flattens, slows, and spreads typically at the exit of a canyon onto a flatter plain. A convergence of neighboring alluvial fans into a single apron of deposits against a slope is called a bajada, or compound alluvial...

. An alluvial fan is a fan

Fan (implement)

A hand-held fan is an implement used to induce an airflow for the purpose of cooling or refreshing oneself. Any broad, flat surface waved back-and-forth will create a small airflow and therefore can be considered a rudimentary fan...

-shaped deposit

Deposition (geology)

Deposition is the geological process by which material is added to a landform or land mass. Fluids such as wind and water, as well as sediment flowing via gravity, transport previously eroded sediment, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of...

 formed where a fast flowing stream

Stream

A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...

 flattens, slows, and spreads typically at the exit of a canyon

Canyon

A canyon or gorge is a deep ravine between cliffs often carved from the landscape by a river. Rivers have a natural tendency to reach a baseline elevation, which is the same elevation as the body of water it will eventually drain into. This forms a canyon. Most canyons were formed by a process of...

 onto a flatter plain

Plain

In geography, a plain is land with relatively low relief, that is flat or gently rolling. Prairies and steppes are types of plains, and the archetype for a plain is often thought of as a grassland, but plains in their natural state may also be covered in shrublands, woodland and forest, or...

.

At Bourne sections have shown highly weathered gravels overlain by sandy silts and clay loams, the highest levels in the sequence
showing evidence of cryoturbation

Cryoturbation

In gelisols , cryoturbation refers to the mixing of materials from various horizons of the soil right down to the bedrock due to freezing and thawing.Cryoturbation occurs to varying degrees in most gelisols...

. Two phases of fan sediment deposition were separated by a long period of subaerial weathering, which may represent an interglacial period.