Mavis Grind is a narrow strip of land that joins the north western part of Mainland Shetland with the larger southern part. It's now approximately 100 meters wide, but according to the Modern Antiquarian it was about half a mile wide during the Neolithic period. On nearby Virdins Hill, on the north west cliff overlooking Mavis Grind, walls and foundations were found (Neolithic?). Julian lists the numerous prehistoric finds have been made on the Grind itself:
...saddle querns made of granite, potlids of micaceous sandstone, whetstones, and small polishers made of softer rocks, grinders, pestles, hammerstones and pounders, all made of tougher igneous and metamorphic rocks.
The evidence seems to point towards the importance of Mavis Grind as a routeway between the two parts of the island, in use for thousands of years.