Some of the best glacial grooves are found on Kelleys Island in Ohio. Gabriel takes us there!
Class Discussion Questions:
1) Create a postcard showing how alvars or glacial grooves are formed.
Read the Script:
Ohio is a pretty groovy place. Wait, not that kind of groovy? You mean glacier groovy? Oh, right, right, right, it's because Ohio is home to the world's largest and most easily accessible glacier grooves in the world. Although, by easy I mean you have to take the ferry far out to Kelleys Island in Lake Erie.
Located on the north side of the island, the grooves are 400 feet long, 35 feet wide, and 10 feet deep. The grooves were carved into limestone here about 18,000 years ago by the huge sheet of ice that once covered part of Ohio.
As the glacier pushed across the area of the Great Lakes and Ohio, it picked up rocks and debris along the way. The glacier pushed and scraped into the ground making striations. Striations are a series of ridges and grooves that all go in the same direction. Unfortunately, this area on Kelleys Island was mined for it's limestone and some of the grooves were removed by miners. So, they were even larger at one point, but we can't see that now.
These grooves aren't the only sign that the glacier was here though. Nearby in Kelleys Island is the North Shore Alvar. An alvar is a flat area of limestone that was exposed by a passing glacier. Alvars are rare, and mainly exist around the Great Lakes, and in Northern Europe. It is difficult for plants to grow in this environment because the glacier scraped off most of the soil. And, yet a few plants manage to hang in there, like the Northern Bog Violet, the Balsmam Sqall Weed, and Pringle's Aster. They actually manage to make the blank stone area look pretty nice.
Alvars are also present on Pawley Island, North of Kelleys Island in the Canadian waters of Lake Erie and south of Kelleys Island on Marblehead Peninsula. From this you can see that the glacier traveled in a southwest direction. As you can see, the rocks here in Ohio were just goin' with the flow.