Glacial Erratics and Time

Glacial Erratics and Time
Glacial Erratics

People living in the southern United States may not be familiar with glacial erratics such as the one in the picture. Glacial erratics are rocks deposited by glaciers that are different from the native rocks in the area. Where we live in southwestern Michigan has many boulders like this. Many of us have at least one of them in our yard. They weigh hundreds or even thousands of pounds. Many years ago, when workers were digging the foundation for a wing of our local hospital, they hit a glacial erratic that was so large no equipment could lift it. They had to break it into smaller pieces to get it out of the way.

What is especially interesting about glacial erratics is that no two of them look alike, and they each have their own mineralogy. Some are a form of granite, some are metamorphic rocks like gneiss or schist, and some are sedimentary rocks like limestone or sandstone. As a public high school science teacher, I used to take my classes to the local gravel pit and have my students see how many different rocks they could find. Once, a girl found what she called “a pretty red rock.” I looked at it and recognized it immediately. It was a piece of jasper conglomerate, a rock only known to exist in an outcrop near Bruce Mines, Ontario – a place where I spent many summers as a teenager.

The question is, how did a piece of rock get from southern Ontario to northern Indiana? I have had students find pieces of pure copper in the gravel pit. There is a copper outcrop in the upper peninsula of Michigan that has the same color and texture as the ones my students found. In fact, almost every rock my students found came from a place far to the north of us where those rocks can be seen in outcrops. It is quite evident to thinking students that running water or wind did not carry those rocks. However, a moving sheet of ice can do it. Today you can go to an active glacier and watch that process taking place.

How long does it take for a sheet of ice to flow from Ontario to Indiana? There are places near Martinsville in southern Indiana where you can find similar glacial erratics. Glaciers bring not only minerals but water to our area. There are hundreds of lakes and ponds in the area where we live. Glaciers are a great tool of God to mold and shape the planet, and we are blessed by what glaciers have given us.
The glacial till we found contained no human remains or tools. The glaciers were there long before humans lived in Indiana. The process of shaping and molding the land took an enormous amount of time, but God created time, and it means nothing to Him. Only human theories and religions demand specific time elements. Truly “with the Lord, one day is as a thousand years and a thousand years as one day” (2 Peter 3:8).

— John N. Clayton © 2023