Stone Shapes

  I am reading an interesting book by Robert M. Thorson called Exploring Stone Walls, A Field Guide to New England's Stone Walls. I thought I would share this bit about the shapes of stones from pages 25-26. There are "eight categories of basic shapes common to stones found in New England Walls:
Blocks are equant and angular.
Balls are equant and rounded.
Prisms are columns that are angular.
Rollers are columns that are rounded.
Books are tablets that are angular.
Disks are tablets that are rounded.
Slabs can be either angular or rounded, but are normally subangular.

Blades are usually angular."