Feats of Clay EarthCache
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The heart of the City of Lincoln is the Gladding, McBean Terra Cotta Works. Immediately under and the rolling hills surrounding Lincoln consist of extensive deposits of Ione formation clay. Huge piles of raw clay are stockpiled throughout the grounds as are finished products.
The Eocene epoch is arguably the most important time in California’s Economic Geology. From the auriferous (gold-bearing) gravels of ancestral rivers to the deltaic clay, specialty sands, lignin and coal of the Ione-Domengine formations, millions of dollars has been mined from these deposits since the Gold Rush and continues to this day.
According to the Bureau of Land Management, the Ione Formation represents the only occurrence of an Oxisol in the continental United States. An Oxisol is an intensely weathered mineral soil typically associated with tropical environments (visit link) . It is direct evidence of a tropical weathering regime in California during the early Tertiary Period.
The Ione Formation occurs as a 200-mile-long series of isolated exposures along the western foothills of the Sierra Nevada, California, between Oroville in Butte County southward to Friant in Fresno County (see Figure 1 (visit link) ). It is comprised of fluvial, estuarine, deltaic and shallow marine deposits of Eocene age and gently dips to the west. The Ione Formation was formed between 65 and 45 million years ago when much of the present land surface of California's Central Valley was inundated by a shallow sea. Weathering of the Ione Formation itself is probably not only related to the Eocene paleo-climate, but also a later extended period of exposure before it was buried (Creely and Force).
While its mineralogical and industrial properties have received considerable attention, until recently the details of its origin and development have not. A recent paper on the type section of the Ione Formation, by Creely and Force, sheds important light on central California's geological history as well as the history of Oxisols worldwide.
According to the Gladding McBean Company Web site, Charles Gladding of Chicago was visiting California in the Fall of 1874 when he read the news of a major clay find. He traveled to Lincoln, took samples of the clay and sent them back to Chicago for testing by ceramic experts. The clay proved to be of excellent quality and was in abundant supply. On May 12, 1875, along with new partners Peter McGill McBean and George Chambers, Charles Gladding returned to Lincoln with a group of skilled craftsmen and Gladding, McBean and Co was born.
In 1884, the company built a two-story office building on Market Street in San Francisco, using terra cotta trim made at the Lincoln plant. The building attracted a lot of attention and in the ensuing years Gladding, McBean and Co became a leader in producing architectural terra cotta facades for some of the most significant historical landmarks around the world. By the early 1890s the company had also expanded its line to include fire brick, roof tile, chimney pipes and ornamental garden pottery. An early clay roof tile project was Stanford University, one of the countries most prestigious and architecturally stunning campuses (visit link) . To this day Gladding continues to provide its signature clay tile to Stanford University for any campus additions, as well as residential and commercial buildings worldwide.
According to Schmitt, very few terra cotta companies survived changing public tastes and the lean years of the Great Depression and World War II. However, Gladding, McBean and Co. operated until 1962, when it merged with Lock Joint Pipe Co. and formed what was known as Interpace Corporation. However, in 1976 Interpace announced their intention to cease operations at the Lincoln plant. Fortunately, Pacific Coast Building Products emerged to purchase the company and restore the famous name of Gladding, McBean. Today the plant is thriving, with proven clay reserves assuring operations for decades to come. Looking toward the future, the biggest threat to the company’s survival is likely to be suburban encroachment on both the plant and the its surrounding clay reserves.
This Earthcache will take you on a tour of the perimeter of the Gladding McBean plant.
In order to claim a find on this Earthcache, please respond to the following:
1. What geologically accounts for the color of the clay products visible in profusion on the other side of the fence from this location? 38 deg 53.810N 121 deg 17.348W
2. How many giant chimneys/smokestacks soar into the sky above the plant?
3. What are the three years visible in a triangle high on the south side of the building? 38 deg 53.667N 121 deg 17.559W
4. Photograph your GPSr with or without you in front of a building adorned with architectural terra cotta manufactured from the Gladding, McBean plant (visit link) 38 deg 53.503N 121 deg 17.442W. If you claim a different building, please include the coordinates with your log.
Please do not post the answers in your log or it may be deleted without notice.
Feats of Clay is an annual pottery event sponsored by the Lincoln Arts and Culture Foundation (visit link) .
References:
Bureau of Land Management Web site, Ione Tertiary Oxisol Soil Area of Critical Environmental Concern (ACEC) (visit link)
Creely, S., and Force, E.R., 2007, Type Region of the Ione Formation (Eocene), Central California: Stratigraphy, Paleogeography, and Relation to Auriferous Gravels, U.S. Geological Survey, Open-File Report 2006-1378 (visit link)
Gladding, McBean Company Web site (visit link)
Schmitt, R.E., 2002, Sullivanesque: Urban Architecture and Ornamentation, University of Illinois Press.
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