Here are two images of English hill figures (The Cerne Abbas giant and the Uffington white horse):
These hillsides, which are obviously grazed by sheep, show tracks that form numerous contour lines around the said hillsides. According to many people, however (e.g., Wikipedia), these contour lines are not generated by domestic livestock.
If that is the case, what causes these lines and why do they only appear on hills that are grazed by livestock? If, on the other hand, no livestock grazes these pastures, what keeps the grass so short and why are English farmers wasting such huge amounts of good grazing land? Are they mad? Some people, such as this answer, say the lines are caused by natural earth movements, but won't explain why they only occur on hills that are grazed by livestock. There are many more examples, and better ones, of chalk hill contour lines available on Wikipedia, but my simple explanation of how to find them has been deleted. The Long Man of Wilmington is a much better example than the two photos above, it shows the sheep as well as contour lines and is available on Wikipedia.