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Not to be confused with the protected gap between Goring-by-Sea and Ferring.

The Goring Gap is a location in southern England where the River Thames, flowing from north to south, cuts through and crosses a chalk escarpment in a relatively narrow gap between the Chiltern Hills and the Berkshire Downs. The Gap is approximately 10 miles (16 km) upstream of Reading and 27 miles (43 km) downstream of Oxford. The Gap is named after the town of Goring-on-Thames in Oxfordshire. That town is on the east bank of the river at Goring Gap, and Streatley (in Berkshire) is immediately opposite, on the west bank.

At Goring Gap, the Thames is at an altitude of about 45 metres. The ground rises steeply on either side, reaching 100 metres within a kilometre to the east and west, and continuing to higher ground at around 160 metres.

The Chalk has proved to be relatively more resistant to erosion than adjacent geological formations, so the relief of land to the north and south-east of the Gap is notably less marked. In particular, there is a low-lying Gault clay vale either side of Dorchester (to the north), and a broad, low-lying London Clay zone in the London Basin beyond Reading (to the south-east).

Although this configuration - of a major river slicing through chalk hills, with extensive areas of lower-lying land on either side - is not found in this precise fashion elsewhere in the Chiltern Hills, it is found at a number of locations in the North Downs and South Downs; for example, where the North Downs are crossed by the River Wey at Guildford, and by the River Mole near Dorking.

The River Thames has its origins in the emergence of Britain from a Cretaceous sea over 60 million years ago. During the latter part of the Cretaceous period, sea level is thought to have been over 150 metres higher than today. Much of the land which was later to form Britain was covered by sea. In this marine environment, thick deposits of Chalk were laid down.

From the early Paleocene (from around 65 million years ago), much of what is now Britain emerged above sea level. The maximum uplift occurred in the north-west, with a regional tilt towards the east and south-east. The North Sea basin also developed.

The drainage of much of England was thus aligned to the south-east. As the land emerged from beneath the Cretaceous sea, precursors of some of today's major drainage systems of central, eastern and southern England developed. Thus, from the early Tertiary period a number of major consequent rivers flowed approximately NW-SE down the tilted emergent Chalk surface towards what later became southern England.

One of those early watercourses was the Ancestral Thames. However, the course of the river prior to the Pleistocene epoch is not known exactly. The geological beds over which it flowed, and any deposits which the river may have left, have all been removed by erosion.

However, it is known with some certainty that the Thames has been flowing close to where the Goring Gap is now situated from at least Early Pleistocene times - that is, for at least one million years, and probably for rather longer. This is because a deposit of "variably sandy and clayey gravel", which is known to have been laid down by the Thames, has been found on hilltops close to Goring Gap. This deposit, known as Westland Green Gravel, lies on land at a today's altitude of about 160 metres at Cray's Pond (about three kilometres east of Goring), and at the top of Streatley Hill (about one kilometre west of today's Thames). It is believed that that deposit was laid down by the Thames approximately 1.6 million years ago.

(It is possible that, at a slightly earlier time (on a geological scale), the Thames may have been flowing on a course a little to the north-east of Goring Gap - that is, through Stoke Row, where deposits laid down by Thames and resting today at a somewhat higher altitude (over 170 metres) have been identified. The outcrops of Thames gravel there are relatively isolated, and the line which the river was taking at that time is not entirely clear. But if the Thames did enter the London Basin in the vicinity of Stoke Row at that time, it would then have moved south-westwards to Goring Gap over a period of about a hundred thousand years or more, prior to the deposit of the Westland Green Gravel. (Footnote - Nettlebed - maybe thames a little further to NE even earlier; but the thames-nature of these deposits have been challenged (ref).)

At WestlandG time, it is thought that the thames had its headwaters somewhere in N Wales; then flowed south through the Midlands, crossed what are now the Cotswolds, then followed roughly the line of today's Evenlode, to enter the LBasin at Goring. Then it turned NE, leaving deposits which have been identified near Goring, then at Bowsey Hill and Ashley Hill (between HenleyonThames and maidenhead), Hodgemoor Wood (near Chalfont St giles), Essendon, then WGreen near Bishops Stortford. It supposedly continued into the NSea basin beyond Norfolk. So it was a much longer river than today's Thames.

The extent and course of the Thames have been considerably changed in certain places during the past 1.5Ma. In particular, it lost its headwaters north of the cotswolds - possibly as a result of the Anglian glaciation about 450K years ago. That glaciation was certainly responsible for a major change in the river's course in the London Basin, where the ice advance to Watford forced the river, which had formerly flowed along the line of the Vale of St albans, to take a more southerly course towards the North Sea, approximately along its present line.

However, the course of the Thames in the vicinity of Goring Gap has stayed much the same during the past 1.5Ma. Deposits laid down by the Thames which are younger than the Westland Gravel are found on hillsides close to today's Thames in a zone running from Goring Gap to Reading, with their altitude becoming lower as the deposits become younger (ref Gibbard 85). And ice sheets from the north never reached as far south as Goring, so they did not disrupt the river's course here as they did elsewhere. The river at Goring Ggap has simply cut down progressively to its current altitude. During that time, the relief in the vicinity of the gap, as elsewhere in many parts of Britain, has become progressively more pronounced as the Quaternary, with its alternating glacial and inter-glacial periods, has proceeded.

Goring Gap Wiki page content to 2024-01-16:

Not to be confused with the protected gap between Goring-by-Sea and Ferring.

The Goring Gap is the narrow valley, occupied by the River Thames, between the Chiltern Hills and the Berkshire Downs. It is approximately 10 miles (16 km) upstream of Reading and 27 miles (43 km) downstream of Oxford. The river here delimits Berkshire from Oxfordshire. The village of Goring, on the Oxfordshire side of the Thames, gives its name to the gap.

Formation

Elevation: slope map with the Goring Gap in the southwest (bottom left) between the white hills. Click for broader map and to enable varied magnification.

Half a million years ago the chalk hills mentioned formed a continuous escarpment, thus the Thames flowed northeastwards to reach the North Sea sharing the catchment of the Great Ouse. A headwater of the latter still comes within 2 miles (3.2 km) of low-gradient Thames tributary the Cherwell in an almost flat landscape. During maxima of the recent ice ages, the plain of the lower course froze, leaving all of northern England covered in ice sheets. The sheets grew to reach a likely previous escape, an overflow via the deep valleys of the Bulbourne-Gade, upper Colne, Stort and Stour. The Thames was thus halted, in a lake submerging the plain of Oxford: a winter-frozen but summer-thawed type. This eventually became so high that it overtopped the escarpment and cut a new route through the chalk, creating the Goring Gap.

Since the ice sheets receded, the Thames has continued its new course – that is, one through Berkshire, to soon meet the River Kennet which had already carved out the lower Thames valley.

Context and localities

The Goring Gap constricts the Thames, narrowing the otherwise broad valley. Downstream lower hills almost face each other at Henley-on-Thames.

Steep hills rise southwards to Lardon Chase, the nearest section of the Berkshire Downs while the Chiltern Hills rise to the north. The twin villages of Goring and Streatley face each other at the heart of the gap. The Thames Path local section between Reading and Oxford, and the Ridgeway (local successor to the Icknield Way) cross the Thames here.

The Goring Gap forms an important communications and transportation corridor. Besides the river itself, which is now limited to navigation for leisure purposes, the gap accommodates the A329 road linking Reading and Oxford, along with the Great Western Main Line railway from London to Bristol and South Wales.

Gallery

The Goring Gap on a summer's evening from Lardon Chase

• 
  A tree-lined part of the Thames in the Goring Gap.
• 
  The river and gap seen from Lardon Chase on a snowy January day, with the Chilterns in the background

External links

• Media related to Goring Gap at Wikimedia Commons