Geology of Northwest Indiana: Glaciers, Moraines, and More!

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Have you ever wondered why our landscape here in Northwest Indiana looks the way it does? And where did all that sand come from? We’re sharing some fun information about the unique geology of Northwest Indiana! 

First, let’s start with some basic geology terms. Sedimentary rocks are rocks that are formed as layers of debris and sediment get compacted and cemented together. This often happens on ocean floors and lake and river bottoms. Examples of sedimentary rock include sandstone, mudstone, and conglomerate. There are two other major rock types – igneous and metamorphic – but we won’t be discussing those today. The second term that’s important to know is bedrock. Bedrock is the solid, un-weathered rock that lies beneath loose surface deposits of soil and sand. In our case, it’s the rock base of Indiana that is deep and expands throughout the whole state.

The bedrock in Indiana is made up mainly of sedimentary rocks; the three main rocks are limestone, sandstone, and shale. In some parts of Indiana, you can see this bedrock in areas where it is exposed but in Northwest Indiana, there are 350 feet of glacial sediments covering the bedrock.

The landscape of this area was highly impacted by the repeated arrival and retreat of glaciers. The first ice sheet arrived in Indiana around 700,000 years ago from what is now Michigan. These glaciers moved sediment like a conveyor belt as they advanced, creating the moraines we still see today. Moraines are hills constructed adjacent to the edges of glaciers from released sediment (they are made of till, which is a mixture of sand, gravel, clay, and rocks of varying sizes – small to boulders). Moraines make up more than half of the land in Porter County. 

Sunset Hill Farm sits on top of the Valparaiso Moraine, which is the largest and highest moraine in Northwest Indiana. It runs parallel to the shore of Lake Michigan. At Sunset Hill Farm, you can see the direct results of glaciers by looking at Roller Coaster Hill, which was likely right at the edge of a glacier. The hill at the Pines Ski Area was formed in the same way.

Glaciers are also responsible for all of the sand we see both at Sunset Hill Farm and at the Dunes of Lake Michigan! This sand was deposited here by glacial outwash, which is different from the glacial till we talked about earlier. Outwash is sediment that was transported and deposited by glacial meltwater, like sand and gravel. The lakes and creeks in this area were also formed by meltwater: Coffee Creek and Salt Creek were both formed by meltwater that flowed out of and under the glacier in large channels.

So the next time you are out admiring the dunes or hiking at Sunset Hill Farm, take a minute to think about and appreciate why the land looks the way it does!