What Are Those Big Concrete Pyramids Down by the River?

What Are Those Big Concrete Pyramids Down by the River? (HM24TO)

Location: Devils Tower, WY 82714 Crook County
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Country: United States of America
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N 44° 35.357', W 104° 42.278'

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Ever wonder what those big concrete pyramids down by the river are? Why are they there? How long have they been there?

Before the Keyhole Dam was built in 1952, the old bridge (built in 1928) across the Belle Fourche River was frequently in danger of flooding during times of high water. Every spring the river would flood, often changing course dramatically.

In 1929-1930 a new channel was cut for the river and 39 massive concrete pyramids (tetrahedrons) were put in place to control the flooding river. In 1933, 33 more tetrahedrons were added. They have been there every single day. The new bridge and dam make them unnecessary - just a curiosity from an earlier time.

During floods, the tetrahedrons helped prevent erosion and the river from changing its path, by supporting the banks.
HM NumberHM24TO
Marker ConditionNo reports yet
Date Added Sunday, January 21st, 2018 at 10:01pm PST -08:00
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Locationbig map
UTM (WGS84 Datum)13T E 523445 N 4937369
Decimal Degrees44.58928333, -104.70463333
Degrees and Decimal MinutesN 44° 35.357', W 104° 42.278'
Degrees, Minutes and Seconds44° 35' 21.42" N, 104° 42' 16.68" W
Driving DirectionsGoogle Maps
Area Code(s)307
Closest Postal AddressAt or near 60 WY-110, Devils Tower WY 82714, US
Alternative Maps Google Maps, MapQuest, Bing Maps, Yahoo Maps, MSR Maps, OpenCycleMap, MyTopo Maps, OpenStreetMap

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