Colman, T…Preston (Merwin’s Business Directory of Minnesota For 1869-70, Heman Merwin, Saint Paul, 1869, Page 88)
Brick. There is no lack of materials for making common red brick. In some places the surface of the drift clay is used, containing some fine gravel, and at others the loess-loam. Brickmaking machinery was met with in the survey of the county at the following points: Preston, Franklin Coleman. (The Geological and Natural History Survey of Minnesota, The Fourth Annual Report, For The Year 1875, N. H. Winchell & M. W. Harrington, The Pioneer-Press Company, St. Paul, 1876, Page 71)
Brick. There is no lack of materials for making common red brick. In some places the surface of the drift clay is used, containing some fine gravel, and at others the loess loam. Brick-making machinery was met with in the survey of the county at the following points: Preston, Franklin Coleman. (The Geological and Natural History Survey of Minnesota, Volume I, 1872-1882, N. H. Winchell and Warren Upham, Johnson, Smith & Harrison, Minneapolis, Minnesota, 1884, Page 321)
Page 100. At Preston is one of the most important of the loess deposits. The section exposed is as follows: Loess loam…6 inches, Yellow loess…10 feet, Bluish gray loess (to an unknown depth)…5 feet exposed.
Page 101. The yellow loess is the part of the deposit being used and the blue-gray material is reported as being too plastic for use in a sand-mold brick plant. The deposit is very extensive and will furnish material for good common red brick for many years. The plant is located about a mile north of town. The plant here has a capacity of 30,000 brick per day and is steadily operated. (Clays and Shales of Minnesota, Frank F. Grout and E. K. Soper, The University of Minnesota, Minneapolis, Minnesota, 1914)