Mystery Nazca Lines - An Explanation?

We were walking to the west of Fascadale the other day when we noticed these lines running across the opposite hillside.  As we walked further along the coast we started to come across the feature that causes them - ditches.  These ditches run across flat land, but also diagonally across hillsides.

We noticed them for the first time last winter (post here), when the vegetation had died back: they stood out very clearly and reminded us of the mysterious Nazca lines of Peru.  At first we thought them to be drainage ditches, but the fact that many of them ran across hillsides that were far too steep for agricultural use made us think again.

On returning from our Fascadale walk, we looked at Bald's map of 1806 to see if the areas they crossed were used as fields in those days.  The Fascadale field systems of the time were limited, and no houses were marked.  Moreover....

....a satellite view using Bing Maps shows them quite clearly as the 'lazy beds' of the rig and furrow system - though the ones in the bottom of the picture, running down a hillside, are the mysterious straight ditches.

But we were shocked when we started to look to the west of Fascadale, where we had walked.  Because the current Bing satellite photographs of the area were taken when the sun was at a low angle, features like ditches are easily visible, and....

....there are hundreds of them, covering many hectares.  In places, they're like a spider's web, and some run across land which could hardly be of agricultural use.  This picture, taking from Bing Maps, shows the network on just one headland.

After the last post on this subject, Sue j c wrote a comment which was very helpful: "I am told by my husband who was told by his elders when he was a wee lad, that a squad of contractors with spades etc dug all these drains by hand to improve the grazing on the estate many many years ago. Some of the men lodged in the old ruined house above Ockle whilst others lodged with local crofters. The last time the Basin was drained it was done by a huge tractor and plough, whilst two Irishmen Peter and Frank widened the burn with shovels."

Some totally unrelated research, into the previous owners of the Ardnamurchan Estate, yielded a reference to the biggest 'improver' of the lands of Ardnamurchan, Sir Alexander Murray of Stanhope, who owned the Ardnamurchan Estate in the early part of the 18th century.

The reference, from the 'Domestic Annals of Scotland, Reign of George I: 1714-1727 Part 5' - link here - includes the statement that Sir Alexander considered that "it was of import­ance to the low grounds that the higher should be drained first".  There's a certain logic in the idea.

Have a look yourself at Sir Alexander's 'improvements' three hundred years on:

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