Clarke Thomson

Georgraphy Intership Coordinator

Postglacial water levels in the Great Lakes Region in relation to Holocene climate change : Thecamoebian and Palynological evidence /

Various lake phases have developed in the upper Great Lakes in response to isostatic adjustment and changes in water supply since the retreat of the Laurentide Ice Sheet. Georgian Bay experienced a lowstand that caused a basin wide unconformity approximately 7,500 years ago that cannot be explained by geological events. Thecamoebians are shelled protozoans abundant in freshwater environments and they are generally more sensitive to changing environmental conditions than the surrounding vegetation. Thecamoebians can be used to reconstruct the paleolimnology. The abundance of thecamoebians belonging to the genus Centropyxis, which are known to tolerate slightly brackish conditions (i.e. high concentrations of ions) records highly evaporative conditions in a closed basin. During the warmer interval (9000 to 700 yBP), the Centropyxis - dominated population diminishes and is replaced by an abundant and diverse Difflugia dominate population. Historical climate records from Tobermory and Midland, Ontario were correlated with the Lake Huron water level curve. The fossil pollen record and comparison with modem analogues allowed a paleo-water budget to be calculated for Georgian Bay. Transfer function analysis of fossil pollen data from Georgian Bay records cold, dry winters similar to modem day Minneapolis, Minnesota. Drier climates around this time are also recorded in bog environments in Southem Ontario - the drying of Lake Tonawanda and inception of paludification in Willoughby Bog, for instance, dates around 7,000 years ago. The dramatic impact of climate change on the water level in Georgian Bay underlines the importance of paleoclimatic research for predicting future environmental change in the Great Lakes.

Charles Clarke Chapman and family, 1890

Studio portrait of Charles Clarke Chapman with his brothers and sisters, 1890. Back row: Charles C. Chapman, Emma Johnson [Mrs. Lewis], Franklin Marion Chapman. Front row, left to right: Colum C. Chapman, Dolla [Harris], Louella [Thamer], Samuel James.

Sketch of Charles Clarke Chapman

Photographic copy of a portrait sketch of Charles C. Chapman in the Chapman College president's office, Orange, California

Charles Clarke Chapman, portrait engraving

Engraved portrait of Charles Clarke Chapman, in book produced by the Historic Record Company, ca. 1911.

Charles Clarke Chapman, Los Angeles, California, 1923

Charles Clarke Chapman, Los Angeles, California, 1923. Photographic portrait taken outdoors, postcard format.

Charles Clarke Chapman

Copy of studio portrait of Charles Clarke Chapman, ca. 1925.

Charles Clarke Chapman, 1942

Photographico portrait of Charles Clarke Chapman, Taken by Bob Gamble, Hollywood, California, 1942

Charles Clarke Chapman, 1942

Studio portrait of Charles Clarke Chapman, taken by the Edwards-Hostetler studio, Los Angeles, California, 1942. Signed on photo mount "Sincerely Yours, Charles C. Chapman."

Charles Clarke Chapman, ca. 1942

Original mounted photograph, signed by the photographer [Hartsook], as well as by C. C. Chapman [Affectionately yours, Father], ca. 1942.

Charles Clarke Chapman, Los Angeles, California, ca. 1895

Studio portrait photograph of Charles Clarke Chapman, Los Angeles, California, ca. 1895

Charles Clarke Chapman, Fullerton, California, 1904

Studio portrait of Charles Clarke Chapman, Fullerton, California, 1904, at the time he served as Fullerton's first mayor.

Home of Charles Clarke Chapman, Fullerton, California, 1914

Home of Charles Clarke Chapman, Fullerton, California, 1914.