There are a few lines in this picture that I took yesterday -
The curved pale line near the bottom is a road; the tiny black blob on it is a car. The two lines at the very top are, as they look, power-lines - they are there because they power this -
The Snaefell Mountain Railway (known locally as the tram) - and, looking back to the top photo, you can see the tram line as the second one up - complete with a tram. There is actually a deep valley between the road and the tram lines.
The diagonal line on the original picture? This was a tin mining area and I'm pretty sure it is one of the many paths through the hills made by the miners.