The claim by the California Division of Mines and Geology that their geologic map can be used to "determine whether the ground on which one plans to buy or build is solid enough to hold the structure" is misleading ("10 Routes to Take," by Laurie Schenden, Nov. 10).
To properly analyze a specific building site many parameters must be measured. Because the average layman has neither the knowledge or tools to perform such analyses, they are better left to the expertise of state-licensed professionals. While the DMG map may be useful to show large structural features such as known faults and rock types, a map of any usable scale to a potential builder would have to be in the range of feet-per-inch to delineate an average lot. Furthermore, the map of two years ago may not show recent changes in buildings and terrain development.
J. A. AMY
and KATHLEEN WHITE