Near Paynesville a brick plant has started work on a delta deposit on the shore of Eden Lake, near the mouth of the incoming creek. The deposit has been excavated to a depth of 16 feet without finding bottom and is known to extend over 8 acres, with a much larger area under the water of the lake. Water had to be pumped from the pit, which extended below the level of the lake, but the seepage through the clay was relatively slow. The clay slaked at once, was highly plastic, and required 21 per cent of water for molding. It shrinks 3 per cent on drying and has a tensile strength of about 150 pounds to the square inch, even when rapidly dried. Burning tests resulted as follows:
| Cone No. | Color. | Shrinkage. | Absorption. |
| Per cent. | Per cent. | ||
| 04 | Salmon | 1 | 22 |
| 01 | Pinkish gray | 2 | 19 |
| 3 | Greenish brown | 8 | 4 |
| 5 | …do | 9 | 3 |
The clay is hard after burning to cone 01 (2,066° F.) and reaches viscosity at cone 6 (2,282° F.). The plant makes stiff-mud brick and has a capacity of 30,000 a day.
Source:
Clays and Shales of Minnesota
Frank F. Grout with contributions by E. K. Soper
United States Geological Survey
Government Printing Office, Washington, D.C., 1919
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