The situations discussed are a result of:

1. Manipulations of surface waters
2. Increasing de-watering of soil and sub-soil
3. Extraction of solids and fluids from underground resulting in decrease of vertical support of overburden of zone of extraction. For this region of the Gulf Coast, and also in the San Joaquin Valley, withdrawal of ground-water is most clearly responsible for surface subsidence.

Examples of (1): Colorado River delta of Texas

(2): Dewatering of base and sub-base of roadways of Texas by trees, particularly in Beaumont, Wheelock of Cook Mountain, Taylor and Naylorville formations.

(3): Sinkholes above Salt Mine and Sulphur Mine

Surface sinking over Wilmington oilfield in California.

Surface sinking in and around areas of heavy ground - water pumping at Baytown and Houston area generally.

Several surveys in wells to show the doglegs, and even parting of pipe, were illustrated.