Goring Gap

The Chalk beds have 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 less marked.

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.

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.

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.

In particular, the Thames lost its headwaters north of the Cotswolds - possibly as a result of the Anglian glaciation about 450,000 years ago.

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.