Tertiary  Late Pleistocene  Holocene 

Our understanding is poor of the timing of the major events that have shaped the terrain of Caithness. This uncertainty reflects the fact that this has been an area of net erosion for much of the last 60 million years. The general sequence of events can be pieced together using evidence from sediments in the North Sea (Johnson et al, 1993) and the continental shelf (Stoker et al, 1993) and from remnants of cover rocks in the Northern Highlands (Johnstone and Mykura, 1989).

We can view the landscape history of Caithness in terms of three main periods, each much shorter than its precursor:

• the Tertiary (65-2.5 Myr) saw the shaping of the main preglacial features of the terrain, the major hills and valleys
• the Pleistocene (2.5 Myr-10 kyr) brought dramatic shifts in climate, with periodic glaciation. Glaciers scoured the sandstones of the plain of Caithness and left thick deposits.
• the Holocene (the last 11.5 thousand years) when climate warmed and sea level rose to its present level