Food From the Land: The Agricultural Interior of North America The Physical Environment

Geology and Topography Primary physiographic region = Interior Plains Beneath almost all of this is sedimentary rock Ex. Sand deposits = Sandstone Calcium carbonate deposits (shells of marine organisms etc) = Limestone Clay deposits = Shale - *The most common sedimentary rock*

How are sedimentary rocks are formed?? 1) Original rock is weathered (broken down into smaller pieces) Elements such as glacial ice, plant roots, wind carried particles , heating and cooling, and chemical reactions all break down rocks.

Sedimentary Rocks Cont…. 2) Weathered particles are transported and deposited. This is known as Erosion and Deposition. Moving elements such as wind, running water, and glaciers erode weathered material.

Sedimentary Rocks cont…. Deposition refers to the ‘dumping’ of weathered material This usually happens under running water, but sometimes occurs over land. Over time the weathered rock material solidifies into sedimentary rock. Strata = A series of layers in S. rock. *Deepest = Oldest Have you ever seen rock like thi before? If so, where?

Fossil Fuels and Energy Minerals in the Canadian Shield/Boreal Shield. Formed in sedimentary rock Formed by the decayed forest or ocean life that thrived in warmer climates, that were later buried. The partially decayed material of marshes, swamps and bogs create the soft, fiber-like material known as peat.

Fossil Fuels cont…. Under pressure, the peat was compressed into strata of coal. High Pressure  Hard, black bituminous coal Low Pressure  Soft, brownish lignite coal **The higher the pressure = darker the coal = the harder it is= “cleaner” burning. (not as much water in it)

Other Fossil Fuels… Other types of fossil fuels are made from tiny, tiny animal life. Petroleum (used for gasoline) and Natural Gas (used in heating), were formed by the body oils of tiny organisms trapped in the sediments and concentrated under pressure! This process took HUNDREDS of MILLIONS of years!!

Topography of the Agricultural Interior The topography of the region is NOT flat! The elevation is lower than that in other regions of N.A. Although, there are lowland areas, most of the surface features gently rolling hills, dotted with irregular features. For example: The Black Hills, the Badlands of MB and Escarpments. (Assissippi Ski Hill!) Dauphin

Topography (features and shape of the land) cont… The main sculpting agents for this region were the glaciers. During the last ONE MILLION years great sheets of ice covered N.A. several times!! (Glaciers are formed when more snow falls in the winter than melts in the summer) As glaciers move they push boulders, stones, gravel and dirt along with them. This material can be left behind as hills and are called moraines. (kind of like a pile of snow you leave Behind when you are shoveling )

Glaciers cont…. As glaciers melt, rivers start to flow underneath the ice. Their bottoms are higher than the surrounding ice. As all of the ice melts away, a long gravel hill like feature called an esker remains. (Parts of the highway from Dauphin to Swan River is built on one!)

Glacial Lakes In some places shallow lakes were formed as the glaciers melted. The largest one was Lake Agassiz , the bottom of which is now the Red River Valley. (That’s Us!) The glaciers melted for the last time 10,000 years ago. The Manitoba lakes are what remain 