Around A.D. 1250, seeking refuge from some unknown threat, the Anasazi migrated from open villages to nearly inaccessible dwellings. A generation later, they moved again. Douglas Merriam In 1874 ...

The physical dimensions of the Eft-90 components are listed in Table 1. This is the preferred layout for ease of use and serviceability. The optimal area is 10 ft by 6 ft, 60 ft 2 (5.57 m 2).