Hot Springs in Fall River County, South Dakota — The American Midwest (Upper Plains)

Paleozoic-Mesozoic Era

~252 million years ago

Photographed by William Fischer, Jr., September 25, 2026

1. Paleozoic-Mesozoic Era Marker

Inscription.

As you move through the Paleozoic Era, life has emerged and spread onto land. The Black Hills are still not yet present, and present-day South Dakota resides near the outer edge of the supercontinent Pangaea. We find few fossils in the area from this time, but the rust-colored rocks around the Black Hills, such as the Spearfish Formation, represent coastal environments of the early Mesozoic Era.

[Illustration caption reads]
Acrolepis gigas, an extinct bony fish from the early Triassic.

Erected by The Mammoth Site of Hot Springs, Inc.

Topics. This historical marker is listed in these topic lists: Animals • Environment • Paleontology • Waterways & Vessels.

Location. 43° 25.469′ N, 103° 29.013′ W. Marker is in Hot Springs, South Dakota, in Fall River County. It can be reached from no nearby street. Marker is along the Mammoth Site entrance walkway. Touch for map. Marker is at or near this postal address: 1800 US Highway 18 Bypass, Hot Springs SD 57747, United States of America. Touch for directions.

Regionally, this marker is in West River.

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It is also in the American Black Hills,

in the Lewis & Clark Corridor,

on the prairies,

and on the Northern Plains.

Globally, it is in North America,

the Western Hemisphere,

the Western World,

and the Anglosphere.

Historically, it finds itself in what was once Rupert’s Land

and also the Louisiana Purchase.

Other nearby markers. At least 8 other markers are within walking distance of this marker: Late Mesozoic Era (here, next to this marker); Mid-Cenozoic Era (a few steps from this marker); Pleistocene Epoch (a few steps from this marker); Paleozoic Era (a few steps from this marker); Precambrian Era (a few steps from this marker); Mammoth Site of Hot Springs, SD (about 600 feet away, measured in a direct line); Woodward Field (approx. 0.4 miles away); Black Hills College (approx. 0.4 miles away). Touch for a list and map of all markers in Hot Springs.

Regarding Paleozoic-Mesozoic Era. Markers and rocks are part of the walk through Black Hills geology leading to the Mammoth Site.

Related markers. Click here for a list of markers that are related to this marker. Follow the markers chronologically through the geologic

Photographed by William Fischer, Jr., September 25, 2026

2. Paleozoic-Mesozoic Era Marker

timeline

Credits. This page was last revised on October 24, 2026. It was originally submitted on October 21, 2026, by William Fischer, Jr. of Reynoldsburg, Ohio. This page has been viewed 10 times since then. Photos: 1, 2. submitted on October 21, 2026, by William Fischer, Jr. of Reynoldsburg, Ohio.