My Senior Independent
Study, beginning in the fall of 2002, is an attempt to reconstruct
the environmental history of Brown's Lake Bog, an area 20 miles
south of Wooster, Ohio. Research for this project began in the
summer of 2002 as part of the Keck
Ohio research experience for undergraduate Geology students.
Figure 1. Working at Brown's Lake Bog
Brown's Lake Bog is a glacial relict bog
created during the last glacial period in Ohio approximately 16,000
years ago. The site is owned by the Ohio Department of Natural
Resources (ODNR) and managed
by the Nature Conservancy. There
is widespread interest in the history of this bog among Biologists
and Geologists as well as local high schools which use the unique
setting as a place for study. In 1966 the area was named a National
Natural Landmark for its natural preservation and unique ecology.
Figures 2 and 3. Driving the coring apparatus into the ground
and extracting the sediment
The environmental history of
Brown's Lake Bog is expressed in the sediment that has filled
the basin since the last glacial period in Ohio. Two sediment
cores were collected this summer from Brown's Lake Bog, each approximately
10 meters in length. Several abrupt changes within the sediment
cores indicate significant environmental changes on a local, regional,
or even global scale. Interpreting and understanding these changes
in the sediment and environment is the ultimate goal of this project.
Figure 4. One meter of sediment ready for analysis
Four types of material make
up the cores from Brown's Lake Bog: peat, gyttja, 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 and gyttja) at the Holocene transition.
Peat is a fiberous organic substance
made of vegetation in various states of decomposition.
Interval: 3 to 9.2m |
 |
Gyttja is a dark organic material
similar to peat, but less fiberous and more compact.
Interval: 9.2 to 9.8m |
 |
Silt is a medium brown to grey
fine grain sediment, silt is refered to as mottled when
it shows certain textures of discoloration.
Interval: 9.8 to 12.3m |
 |
Diamicton is composed of silt,
sand, and larger pebbles. Diamicton in a glacial environment
is refered to as till.
Interval: 12.3 to 12.35m |
 |
The sediments from Brown's Lake
Bog represent environmental change since the last glacial period
in Ohio. The variety in the materials shown above indicate that
Brown's Lake Bog has been a vaslty different depositional environment
over this time. Several studies such as Shane and Anderson (1993)
have isolated as many as four significant periods of climate and
biological change in northeast Ohio and throughout the Midwest.
The challenge of this study is to compare the information yielded
from sediments at Brown's Lake Bog to these other studies.
References:
Shane, L.C.K. and Anderson, K.H. (1993). Intensity, gradients
and reversals in late glacial environmental change in east-central
North America. Quaternary Science Reviews, 12, 307-320.
Yu, Z. and Wright Jr., H.E. (2001). Response of interior North
America to abrupt climate oscillations in the North Atlantic region
during the last deglaciation. Earth-Science Reviews, 52,
333-369.
Links:
An article
about Keck Ohio from the University of Cincinnati.
Pictures from the Keck Ohio group and our trip to the Canadian
Rockies.