06:30Good Morning DevonDartmoor National Park Authority warns mine shafts up to 100ft deep could collapse because of the bad winter.BBC Radio Devon Duration: 2 hours, 30 minutes Fri 2nd May 2014, 06:30 on BBC Radio DevonNews and features with weather and travel every 15 minutes presented by Matt Woodley.GenresNewsBrandGood Morning Devon Source: BBC Online