Bucks Earth Heritage Group

Olney

Grid reference: SP 890 510 (for the church)

Area of interest: the town centre buildings

Access, location and parking: Easy access via the A509 and easy parking at many locations.

Geological summary: This is an excellent locality to see local building materials put to their best use.

The geological story starts as you approach Olney. Here the flat and featureless landscape of the Jurassic clays (from the Oxford Clay in the Milton Keynes area to Lower Lias clays in the Olney area) transforms into the harder limestone ridges outside Olney. Landscape shows a direct geological control in this area. The softer rocks wear down to form the vale and the harder rocks form the ridge and hills. This is also true of the effect of the Ouse as it flows through this part of the valley, cutting its valley and leaving behind a series of previous terraces.

The Ouse at Olney - a quiet meandering river

Olney is a pretty little town using much of the Jurassic limestones of the area. Buildings using the Blisworth Limestone and/or Upper Liassic limestones are: the Cowper Museum , the Parish Church of St Peter and St Paul (see photos below), the Olney Centre (which used to be the old Victorian school, below), the Old Maltings, and numerous private houses, walls and rockeries in the village along Bridge Street, the Market Place and Weston Road. All the characteristic features of the rock types can be seen including lithology, sedimentary structures and fossils.

The church of St Peter & St Paul

The church is particularly interesting geologically as it uses a mixture of all types of local rocks: Liassic limestones, newer (Victorian) Portland Limestone repairs, ironstones, sandstones and a large calcite block (source unknown). Other rock types can be seen in the church graveyard: more local limestone, but also Italian marble, Peterhead Granite (from Scotland ) and Dartmoor Granite (from Devon ).

Granite from Scotland - one of many exotic rocks in the churchyard

The gate to the Church of St Peter and St Paul , Olney. Many different limestones have been included in this gate pier, some local and others from Lincolnshire or Bath, as repairs were needed.

The gate piers are an interesting mixture of several repairs as stone masons struggled over the years to make a good match to the original Blisworth Limestone used in the original structure and most of the surrounding walls.  Weldon, Portland , Bath and Blisworth Stone can all be found in the structure. Although they are all Jurassic limestone,, they weather very differently resulting in the varying colours and amount of decay. The Portland Limestone for instance is the palest block (not labelled) and becomes paler with weathering and age.

The Church Hall, Olney