The Environmental Record of The Hartley Bog Mastodon Site, A Glacial Bog

James Martin, The College of Wooster
Department of Geology

Research for this project began in the summer of 2002 as part of the Keck Ohio research experience for undergraduate Geology students.  Then in Fall 2002 back at my college I have been continuing my research of the Hartley Mastodon Site, Columbiana County, Ohio.   

Figure 1. Hartley Bog Mastodon Site core location.

The Hartley Mastodon Site is a glacial bog created during the last glacial period in Ohio approximately 16,000-18,000 years ago. The site is owned by George and Donna Jackson, they had found a Mastodon skeleton in a different area of the bog.  Other parties that are interested in this bog are Cheryl Mattevi (Kent State Univ, Salem Campus) and Mandy Munro-Stasiuk (Kent State Univ, Kent OH).

Figures 2.  One of the other undergraduate students on the Keck project was Jen New from Whitman College.  In her hand is the Modified Livingston Corer we used to core the Hartley Bog Mastodon Site.

 The Modified Livingston Corer is driven into the ground and then pulled back out full of sediment which is then extracted and wrapped for transport.

The environmental history of Hartley Bog Mastodon Site is expressed in the sediment that has filled the basin since the last glacial period in Ohio. Two sediment cores were collected this summer, each approximately 6 meters in length. Several dramatic changes within the sediment cores indicate significant environmental changes. Interpreting and understanding these changes in the sediment and environment is the ultimate goal of this project.

Figure 3. One meter of sediment ready for analysis

Three types of material make up the cores from the Hartley Bog Mastodon Site: peat, silt, and diamicton. These sediments are a classic deglacial sequence representing the changes from glacial (diamicton) to lake (silt) to the rise in vegetation (peat) at the Holocene transition.

Peat is a fiberous organic substance made of vegetation in various states of decomposition.
Interval: 2 to 4m


Silt is a medium brown to grey fine grain sediment, silt is refered to as mottled when it shows certain textures of discoloration.
Interval: 4 to 7.4m


Diamicton is composed of silt, sand, and larger pebbles. Diamicton in a glacial environment is refered to as till.
Interval: 7.4 to 8.4m


The sediments from Hartley Bog Mastodon Site represent environmental change since the last glacial period in Ohio.  Using magnetic data from the core I will attempt to reconstruct this environmental record.


Figure 4. This shows my initial magnetics data from my cores, labeled A and B, which was done during the summer of 2002.  The big spike at the bottom which goes off the graph is the diamicton.


An article about Keck Ohio from the University of Cincinnati.

Pictures from the Keck Ohio group and our trip to the Canadian Rockies.