The River Sid is a minor river in East Devon

East Devon

East Devon is a local government district in Devon, England. Its council is based in Sidmouth, and the largest town is Exmouth.The district was formed on 1 April 1974 by the merger of the borough of Honiton with the urban districts of Budleigh Salterton, Exmouth, Ottery St. Mary, Seaton, Sidmouth...

. It flows for 10.5 kilometres southwards from a source in Crowpits Covert (OSGB36 Grid reference SY138963) at a height of 206 metres above sea level. The source is at the head of a goyle or small ravine.

The underlying geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

 is impermeable silty mudstones and sandstones of the Triassic

Triassic

The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...

 Keuper marl

Keuper marl

Keuper marl is the former name for a layer of mudstones and siltstones from the late Triassic period . Typically red, or occasionally...

, overlain with permeable Greensand

Greensand

Greensand or Green sand is either a sand or sandstone, which has a greenish color. This term is specifically applied to shallow marine sediment, that contains noticeable quantities of rounded greenish grains. These grains are called glauconies and consist of a mixture of mixed-layer clay...

 and clay-with-flints. The junction between the Greensand and Keuper Marl forms a spring line.

The river flows through Sidbury

Sidbury

Sidbury is a village north of Sidmouth on the A375 road in East Devon, England.It is situated on the River Sid, which rises at Ottery St Mary and runs for to Lyme Bay at Sidmouth...

 and Sidford

Sidford

Sidford is a small village in the civil parish of and on the outskirts of the town of Sidmouth in the English county of Devon. It has a population of just over 2100 people according to the 2001 Census....

 to Sidmouth

Sidmouth

Sidmouth is a small town on the English Channel coast in Devon, South West England. The town lies at the mouth of the River Sid in the East Devon district, south east of Exeter. It has a population of about 15,000, of whom 40% are over 65....

and is fed by springs flowing from East Hill and water from the Roncombe Stream, the Snod Brook and the Woolbrook. In Sidmouth the river outflows at the Ham through a shingle bar.