The only fossils found here were fresh-water mussel shells, which occurred in considerable numbers upon a space four rods in diameter near the middle of Gregg & Griswold’s excavation, lying in the upper foot of the clay, just beneath the till. Brickmaking was begun here twelve years ago, and has been steadily increasing to the present time. The first yard worked has been now owned by Gregg & Griswold six years. Their yearly product is about 2500 thousand, selling at $5 to $6 per M [1,000]. From 40 to 50 men are employed for six months. Sand is mixed in varying proportions according to the quality of the clay, the average being about one part in ten. This company have machinery and room to make 40 thousand bricks daily. (The Geological and Natural History Survey of Minnesota, The Eighth Annual Report for the Year 1879, Submitted to the President of the University, Feb. 18, 1880, The Pioneer Press Company, St. Paul, MN, 1880, Page 118)
Gregg & Griswold…Chaska (Minnesota State Gazetteer and Business Directory including Dakota Territory 1880-81, Volume II, R. L. Polk & Co. and A. C. Danser, St. Paul and Detroit, Page 978)
At Chaska the clay used for brick-making is modified drift of interglacial age. It varies from 20 to 40 feet in thickness, being underlain by sand and covered by till from two to six feet thick, holding boulders of all sizes up to five or six feet in diameter, many of which are planed and striated. This till forms the surface, 30 to 35 feet above the river. The only fossils found here were fresh-water clam shells, which occurred in considerable numbers upon a space four rods in diameter near the middle of Gregg & Griswold’s excavation, lying in the upper foot of the clay, just beneath the till. Details of several very interesting sections in these deposits are given on a following page, in connection with notes on the manufacture of bricks. In brief, this interglacial clay, overspread by till, testifies that an ice-sheet covered this region after the Minnesota valley had been eroded nearly as it now is. (A Report on the Geological and Natural History Survey of Minnesota, 1882-1885, Volume II, N. H. Winchell and Warren Upham, Pioneer Press Company, St. Paul, Minnesota, 1888, Page 133)
Page 141. The first yard worked has been owned by Gregg & Griswold ten years. Their yearly product is from two and a half to three millions, selling at $5 to $6 per thousand. They also make faced brick, at $8 to $10 per thousand. From forty to fifty men are employed for six months. Sand is mixed in varying proportions according to the quality of the clay, the average being about one part in ten. This company have machinery and room to make forty thousand bricks daily. The section at Gregg & Griswold’s excavation, 250 feet in length from northwest to southeast, 150 feet wide, and 25 feet deep, has 3 to 5 feet of very coarse till at the top, yellow (except the one or two feet of black soil next to the surface), showing imperfect stratification in a few places, but mostly unmodified, and containing numerous boulders, some of which are glaciated, of all sizes up to six feet in diameter. Next below in the southeast part of this pit, but not in its northwest part, is stratified yellow sand, 1 to 6 feet thick. These deposits are underlain by yellowish clay, about 10 feet thick, its upper portion for
Page 142. two to four feet being rejected because more or less filled with calcareous concretions, a half to one inch thick, while its lower part, from which these are absent, makes good bricks. This clay, colored by the oxidation and hydration of its iron through the action of infiltrating water, is irregularly stratified and much contorted, and holds pockets of sand, one to five feet in diameter. Its lower line is irregular, undulating three to four feet in slopes of 45°, and is in some places partly interstratified with the underlying dark bluish clay, which is excavated 10 to 15 feet vertically, and reaches at least 15 feet more below this pit, not being penetrated at that depth. This dark clay is very compact; it is laminated, but not conspicuously; and nearly all of it is quite irregularly contorted and folded. It rarely contains vertical seams of yellow clayey sand, extending down three feet from the overlying bed, and also small pockets of the same yellow sand, a foot in diameter, apparently isolated at one or two feet below the top of this blue clay. It also includes sandy masses of the same dark color as itself, varying from two to ten feet in diameter, concentric or indistinct in their lamination, apparently entirely surrounded by clay, with definite separating lines. These beds, below the stratum of till at the surface, in this and all the excavations here described, are free from all gravel and boulders, except that perhaps a half dozen fragments of rock, varying in size up to six inches or a foot in diameter, are found in the clay-digging of a whole summer. When this pit was first opened, in the central part of its present area, many bivalve shells were found over a space of four rods or more in diameter, occurring some five feet below the surface, under the till which had boulders here up to five or six feet in diameter, lying in the upper foot of the yellow clay, or in some thin bed between that and the till. These shells were three to four inches long, "such as are found in rivers and lakes of this region." They were the only fossils that have been found in these pits, which have yielded no pieces of either wood or lignite. (A Report on the Geological and Natural History Survey of Minnesota, 1882-1885, Volume II, N. H. Winchell and Warren Upham, Pioneer Press Company, St. Paul, Minnesota, 1888)
The ownership of the several yards in 1884, and statistics of their business, were stated in the Minneapolis Tribune as follows: Gregg & Griswold have forty men, burn 1,500 cords of wood, and will fit contracts to the extent of 3,000,000. (A Report on the Geological and Natural History Survey of Minnesota, 1882-1885, Volume II, N. H. Winchell and Warren Upham, Pioneer Press Company, St. Paul, Minnesota, 1888, Page 145)
Gregg & Griswold, Chaska, Minn. (The Railroad, Telegraph, and Steamship Builders’ Directory, The Railway Directory Publishing Co., New York, 1888, Page 41)