Hi Messy,
Yes, thanks, I did receive the files. The noise is due to small cliffs and terraces generated as a result of the small but non-zero setting you used for the cliffs/terraces overlays (16/100), which are being highlighted because all other terrain effects (i.e. fractal noise, erosion) have been turned off. If you turn off the cliffs/terraces altogether, the effect goes away.
Here is the map with cliffs/terraces = 16:
..and the same map with cliffs/terraces = 0:
Note in the second image, where I have all heightfield effects turned off, you can still see some slight pinprick-like noise. This is an artifact of the diamond/square fractal algorithm that occurs when the fractal roughness is small or zero. Some mild erosion will erase this noise. Alternatively, the 'Operations->Heightfield->Smooth [curvature]' function should wipe out any remaining noise.
For completeness, here is the same location of the same map, where the default strengths have been used for erosion, cliffs/terraces, and noise settings:
Best regards,
Aaron.