This gravel at the side of seems to be a feature of many recent road projects,
Saddell brae, Moy to Stewarton, also near Tayinloan.
-as already suggested it may be to assist water run-off, also low maintenance verge compared to grass which needs constant cutting through the summer months.
It does seem to present serious risks to road users though, not only potential windscreen damage, I would suggest it also presents a serious risk to motorcycles/cyclists both from flying debris and also getting the stuff under their wheels.
I have noticed a couple of times that some non local HGV drivers when passing other wide vehicles mistake these gravel verges as 'part of the road' without slowing down and that really does send a huge trail of debris out behind them. Not good
