Bedfordshire is an area of diverse attractions ranging from stately homes and sleepy country villages to major tourist attractions, bustling towns and attractive countryside. Whether you are looking for a great day or evening out, are visiting or already live here, Bedfordshire has something to offer all ages and interests. Whipsnade Wild Animal Park deserves a full days outing to fully appreciate the thousands of animals found within 600 acres of open countryside. There are rare and exotic animals, a Discovery Centre, and even a steam railway chugging through the animal herds. In addition to the usual animal activity programme a number of special events takes place throughout the year. The southern end of the county is part of the chalk ridge known as the Chiltern Hills. The remainder is part of the broad drainage basin of the River Great Ouse and its tributaries. Most of Bedfordshires rocks are clays and sandstones from the Jurassic and Cretaceous periods, with some limestone. Local clay has been used for brick-making of Fletton style bricks in the Marston Vale. Glacial erosion of chalk has left the hard flint nodules deposited as gravel – this has been commercially extracted in the past at pits which are now lakes, at Priory Country Park, Wyboston and Felmersham.