Ellie Harrison and Matt Baker are in the Peaks in Derbyshire, looking at how the geology there gives rise to two distinct landforms - the Dark Peak and the White Peak. Matt is in the White Peak discovering that the limestone that characterises the region is the remnant of an ancient tropical reef. He ventures underground to see how the action of rainwater down the millennia has carved fabulous forms and caverns, which gave rise to the area's chief industry - lead mining. Ellie is in the Dark Peak, where it's gritstone that marks out the landscape. She takes a walk with an artist who maps the land and creates three-dimensional maps in metal. Ellie then ventures further north to catch a glimpse of England's last remaining population of mountain hares. At this time of year they shed their dull coats for cloaks of white. But, as Ellie discovers, this could make them vulnerable in a changing climate. Sean Fletcher is at Haddon Hall helping with some of the restoration of this famous building. He visits the quarry where they get the gritstone to make the repairs, and he gives Haddon's fabled gargoyles a wash and scrub. Also in this programme, Adam Henson recounts the story of the tractor, from its origins in the age of steam to the hi-tech GPS-guided self-driving tractors of today. And he gets to try his hand at building one. Wild boar had been extinct in Britain for at least 300 years, but now they are back. In the Forest of Dean alone there are now thought to be more than 1000. But, as Tom Heap has been finding out, not everyone is pleased to see their return.