What physical evidence do we have in Ohio that supports that glaciers were present in our past?
Glacial Landforms. Many of the hills, valleys, and ridges across the glaciated two-thirds of Ohio have been shaped by glaciers. These features are called glacial landforms, and they help geologists understand how glaciers moved across the landscape.
What evidence shows that the earth was once covered with glaciers?
The dropstone stratum was evidence of glacial conditions. The fact that this stratum appeared all over the world in land areas was evidence for extensive glaciation at least on land areas. The carbonate rock is formed only in warm seas. This would indicate a warming and melting of the glaciers.
How do scientists know about past ice ages?
How do we know about past ice ages? Scientists have reconstructed past ice ages by piecing together information derived from studying ice cores, deep sea sediments, fossils, and landforms. Ice and sediment cores reveal an impressive detailed history of global climate.
What is evidence of past glaciation?
More evidence comes from glacial striations – scratches on the bedrock made by blocks of rock embedded in the ice as the glacier moves. These show the direction of the glacier, and suggest the ice flowed from a single central point.
How do I find evidence of glaciation?
Such erratics provide evidence of glacial flow lines. Examples include omars, jasper conglomerates, and tillites. Other evidence for glaciation is recorded on some bedrock surfaces beneath the glacial drift. Scratches made by rocks frozen into basal ice scraping over the bedrock are called striae.
What does evidence of erratics indicate?
Yellowstone National Park may be ice-free today, but boulders (called “erratics”) dropped by ancient glaciers indicate that it wasn’t always this way. NPS Photo/J Scmidt. We can tell where glaciers were a long time ago by looking for glacial landforms and features.
Why are erratics found in strange places?
Erratics are significant because: They can be transported by glaciers, and they are thereby one of a series of indicators which mark the path of prehistoric glacier movement. Their lithographic origin can be traced to the parent bedrock, allowing for confirmation of the ice flow route.
What can we learn from erratics?
Some erratics are useful to scientists because they are of a distinctive rock type, which means that their source outcrop can be identified and located. Glacial erratics are therefore useful in reconstructing past glacier flow directions, the timing of glacier retreat, and even the type of glacier flow.