A Drive Along An Ancient Beach EarthCache
A Drive Along An Ancient Beach
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Mina inspects beach ridges of current Lake Erie
Welcome to Ground Zero of this Earthcache! You are currently at the intersection of State Route 108 and Fulton County Road B. If you take a look to the north, you see about a 1/2 mile away, a rather sharp incline 108 passes over. If you look westward back along C.R. B, about a mile back, you see a similar rise. This is because those are both points along an ancient beach ridge and if it were some 13000 years ago, you would currently be underwater in an ancient lake.
The Great Lakes basin was once covered in glaciers. About 15,000 years ago the last ice melted to expose the lake basin. As they receded, the glaciers left behind a newly carved landscape and ancient lakes. As the glacial waters flowed from the area into the Atlantic Ocean, the Great Lakes were formed but it was only until recently that we have the shape the Great Lakes have today.
About 15,000 years ago, the last of the ice melted causing the level of the water in the lakes to rise and fall. Many ancient lakes came to exist over where Lake Erie currently resides. Most remained for hundreds of years. They rather quickly changed into smaller lakes when new outlets for the water occurred and there were even instances when the lakes increased in size when the outlets got blockedby glacial movement. As the lakes moved, they left behind beach ridges.
Most of the lakes have basins with flat, gently sloping floors. Over time as the wind creates waves, currents are produced that carry sand and stone to the edges forming beaches. These beach ridges are our way of discovering the boundaries of these pre-Lake Erie, when the elevation of the lake was much higher than it is today.
The beach ridges were used for traveling for a variety of reasons. The bedrock surface on each side of the ridges is covered by glacial till. These areas are generally swampy due to low relief and poor drainage. Therefore, the buffalo in Ohio's early history chose beach ridges for their trails. The Indians followed the same trails and settled at points along these routes. When the settlers moved into and across the state, they also followed these "established routes," as did the modern highway builders.
The beach ridge road we are looking at once connected the Ottawa and Potawatomi Indians as a trade and hunting route from their encampments around Defiance, Ohio to the area around Wauseon and Delta, OH, now three counties away. This road now goes under many names as it travels though Defiance, Henry, and Fulton Counties. You can travel almost the entire distance of this remaining beach ridge along Adams Ridge/Henry County C.R. X/Fulton County C.R.s AC, EF, and FG.
Blue=ridge road Yellow=ancient beach ridge
To qualify for this Earthcache, please perform these three experiments. Luckily, these can be done from a car, truck, or whatever your favorite mode of geo-travel may be. The OPTIONAL can be done in your own backyard, flower pot, or anywhere else someone may let you. Please do not post your answers in your log. Please use the Message Center to send your answers to TeamMina.
1. Traveling along any section of this route, you can see by looking towards the South and East how the ground slopes down along the ridge road, signifying where the beach ridge fell down into the lake. How high were these early Lake Erie beach ridges? Take an altitude reading at N 41° 30.045 W 084° 09.220 (Reference point waypoint). Take another reading about 100 yards down the road to the south or the east. Calculate the difference between the two as the height of the beach ridge.
2. The ancient lakes of the Lake Erie Basin as best defined by their elevation (to sea level). Drive along this ridge road and take a few altitude readings. Use this information to determine which Ancient Lake beach you are currently traveling on:
LAKE & ELEVATION OF BEACH RIDGE IN FEET
A. Erie ..............................573
B. Lundy ..........................620-640
C. Warren ........................690
D. Wayne .........................660
E. Whittlesey ...................735
F. Arkona .........................690-710
G. Maumee III .................780
H. Maumee II ..................760
3. Determine the length of this ancient beach ridge. This can be rather easily done by:
-Drive the length of the ridge road, with plenty of nice caches to find along the way.
-Measure length of road from map. Scale is easy to calculate as there is one mile between standard county roads in Henry and Fulton counties.
(OPTIONAL COMPLETELY SILLY TASK) Create your own mock glacial lake on your own. Take an ice cube. Place it in some soil or sand and in a location preferably warm or even hot. 1. What physical process is affecting the ice cube? 2. After the water has disappeared, how would you describe the land (soil) left if viewed on a larger scale. Feel free to take a photo of your miniature glacial lake, and/or let us know what what you named it. You could even measure it's size and elevation if so inspired.
Reference: "What Evidence of Glaciation Exists in the Great Lakes Region?" Coastal Processes: COSEE Greatest of the Great Lakes—A Medley of Model Lessons ES-EAGLS—Land and Water Interactions in the Great Lakes ©The Ohio State University, 1996.
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