"Blakey Topping is a natural hill, but from the right direction (including from the stone circle) it is very Silbury-esque".

That's the wrong way round, I think. Silbury is Blakey Topping-esque. Silbury is also very Sugarloaf Hill-esque. Now we need to find a word to replace the name of these hills. If you find a fossilised raindrop, in sandstone, and turn it the other way up, then you get the shape. It's not really a fossilised raindrop - it's the mark made in wet sand by a raindrop or hailstone. Anyone working sandstone, in times gone by, will have encountered these.