Urban Biographies, Ancient and Modern

Detroit, USA

x Excavated soil block
x Excavation of soil block for exhibition
x Artifacts found during excavation of soil block
x Multispectral satellite image of Detroit’s North End
x 1951 Sanborn fire insurance map of North End of Detroit
x 2018 satellite image of North End of Detroit

Satellite Images

Different kinds of vegetation reflect light differently. These variations can be recorded in multispectral satellite images, which isolate and capture different wavelengths across the electromagnetic spectrum. Analysis of multispectral images can help distinguish between “natural” vegetation, such as grass and forest, and cultivated crops. Archaeologists use multispectral images to identify farmland, which is more suitable for archaeological survey than forest or open pasture. Multispectral imagery can also be useful in measuring the impact of urban farming and the transformation of residential neighborhoods in Detroit, and in planning for the future.

Excavation of soil block for exhibition
Multispectral satellite image of Detroit’s North End

This image of the area around Detroit’s North End and the Oakland Avenue Urban Farm uses data from near-infrared wavelengths to measure the density of vegetation, shown here in green. As technology advances and the resolution of multispectral imagery becomes more refined, it will eventually be possible to discern and measure even small-scale land uses such as urban agriculture.

Soil Sample

Farmers routinely sample the fertility of their soil. Archaeologists use soil cores (vertical soil profiles) to preview excavation areas, for example, to determine how deep ancient remains are buried. Soil samples in Detroit are being used for both purposes: to test the soil for nutrients or possible contaminants, and to capture a glimpse of the history of a small part of the city.

Excavated soil block
Excavated soil block in place in former back yard at Oakland Avenue Urban Farm

This soil sample is a vertical block of earth excavated from a former residential property at 9174 Goodwin Street, now part of the Oakland Avenue Urban Farm in Detroit’s North End. Extracted near a back alley where a garage once stood, it shows buried building materials and trash mixed deep into the fine sediments below the topsoil. Near the bottom of the block is a layer of dark organic soil, and below that can be seen the upper part of the sand layer deposited by the ancient lakebed.