The history of most places is determined by their geology.  Mere lies in a special place - right on the edge of the chalk downland and overlooking the flat clay Blackmore Vale.

Outline geology of the Mere district with a section A-A'

Source: Geological Survey - Derek C. Findlay

The phrase 'chalk and cheese' has been used to describe this area - the dry chalk downs and the heavy clays, only useful for pasture, cows and milk production.

Many millions of years ago a massive earthquake caused a fault line which runs through Mere - almost parallel with and just south of Salisbury and Castle Streets. The area to the south of the fault line rose up bringing the underlying clay to the surface.  So people who live in the north of Mere tend to garden on good quality loam containing sand and chalk; whilst those to the south garden on heavy clay. For this reason most of old Mere and the main road to the West Country developed on the best and driest ground north of the fault line.  Most of the houses to the south of the fault line were built in fairly recent times when building land became harder to find.

The chalk layers beneath the downs slope down towards Mere - see diagram. Rain falling on the downs seeps down through the chalk until it reaches the impervious clay and then runs downhill on the surface of the clay until it meets the fault line where it emerges as springs.  The chalk downs, despite all the evidence of early activities by man, suffered from the complete absence of surface water supplies and the presence of assured water must have made settlement by the springs an attractive proposition. Mere and its neighbouring hamlets are in fact a classic example of springline settlement.

The Ashfield Water and Shreen Water carry away some of the outflow from the springline and it was on these that most of the mills were sited.

The edge of the downs here is not a smooth cliff-like feature. Instead it is cut into by the massive dry combes of Great Bottom, Chatcombe Bottom, Aucombe Bolton and Ashfield Bottom.

Although the area to the south with its heavy and waterlogged soils must have made travel difficult, two low ridges run southwards from either end of Mere - the "Causeway" heading towards Shaftesbury and also the line of the Gillingham road - which would have provided reasonably good communication to the South, involving in each case only one small river crossing.

Many of the houses and walls in Mere were built with the local stone from Dead Maid Quarry at the western edge of the town. Chalk for agricultural purposes was quarried at the eastern side of Mere at Charnage chalk pit and flints used to be quarried from the downs for road making.  The disused quarry on Whitesheet Hill is now a nature reserve.