Thomas Harris Smith, designed in the Italianate style and completed in 1860. Geography The main geological feature in this area of the Mendip Hills south of Hallatrow consists of Supra-Pennant Measures which includes the upper coal measures and outcrops of sandstone. The relics of the industrial past are very evident within the area, including the distinct conical shape of the Old Mills batch overlooking the town. Midsomer Norton lies on the River Somer which rises to the west of Chilcompton and on the Wellow Brook which rises near the village of Ston Easton. The town therefore occupies two valleys of the Mendip Hills and these merge west of Radstock. The combined river then flows east reaching the River Avon near Midford, thence to Bath and through Bristol into the Bristol Channel at Avonmouth. On the southern fringes of the town is the Silver Street Local Nature Reserve, on the site of the estate of Norton House, an eighteenth century mansion built by the coalmine-owning Savage family but demolished in 1937-8. It contains a broad-leaf woodland around several ponds, a restored nineteenth-century wellhead that supplied water to the house, and a grassland field. The woodland is leased to the Somerset and Dorset Heritage Railway Trust by Bath and North East Somerset Council and the meadow in the stewardship of Somervale School. Along with the rest of South West England, the Midsomer Norton has a temperate climate generally wetter and milder than the rest of England. The annual mean temperature is about 10 °C (50 °F) with seasonal and diurnal variations, but the modifying effect of the sea, restricts the range to less than that in most other parts of the United Kingdom. January is the coldest month with mean minimum temperatures between 1 °C (34 °F) and 2 °C (36 °F). July and August are the warmest, with mean daily maxima around 21 °C (70 °F). In general, December is the dullest month and June the sunniest. The south-west of England enjoys a favoured location, particularly in summer, when the Azores High extends its influence north-eastwards towards the UK. Cloud often forms inland, especially near hills, and reduces exposure to sunshine. The average annual sunshine is about 1,600 hours. Rainfall tends to be associated with Atlantic depressions or with convection. In summer, convection caused by solar surface heating sometimes forms shower clouds and a large proportion of the annual precipitation falls