The Goring Gap is a British geological feature that is located on the River Thames, approximately 10 miles (16 km) upstream of Reading and 27 miles (43 km) downstream of Oxford. The river here forms the county boundary between Berkshire and Oxfordshire.
Half a million years ago the River Thames flowed on its existing course through Oxfordshire, but then turned northeast to flow through Hertfordshire before eventually reaching the North Sea in East Anglia near Ipswich. During the last ice age, the ice sheet blocked the river's exit to the sea, whilst the amounts of melt water entering the river caused it to pond up into a lake. This eventually cut a new route through the chalk at the site of the Goring Gap. The newly formed route then flowed through Berkshire and present day London before finally reaching the North Sea.
Today, the Goring Gap constricts the River Thames, narrowing the otherwise broad river valley. 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 straddle the River Thames at the Goring Gap.
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.