Ice Age in Nebraska
Among the many discoveries of these Niobrara expeditions
was something NOT reported in the official records.
It was found when the archeologists dug down to excavate a cache pit
-- that's a hole dug into the ground, inside a dwelling, then lined with rocks and clay,
and used to store food for future use.
Not exactly a modern refrigerator,
but the ground is cool even in the Summer
and a cover usually keeps the rodents out.
As they were digging out the bottom layers around the cache pit,
one of the workers notices an oddly-shaped rock in the dirt underneath
and called it to the attention of the supervisors
(my father and Alexis Praus).
Upon examination, it turned out to be a bone,
but it obviously was NOT a Ponca bone.
It was well below the floor of the dwelling,
in layers of sediment that were deposited BEFORE the end of the Ice Age -- a few thousand years earlier.
They took pictures of the layers of earth,
to show that it was found "in situ",
then cleaned off the bone and labeled it.
It was part of a skull, but the thick brow ridges and shallow slope of the forehead was more like a primitive Neanderthal,
rather than the modern humans who had crossed the Bering Straits
AFTER the end of the Ice Age.
However, this evidence was at variance with the "accepted" theories,
that no humans were in North America before the end of the Ice Age (about 10,000 years ago).
Dr. Ales Hrdlick,
a staunch proponent of the "accepted" chronology
(and very-influential authority in the field),
objected strongly to the inclusion of this item in the reports.
Refusing to even look at the photographs showing that the skull bone was found "in situ"
(with the soil layers intact above it),
he insisted that it must have been a "burial by intrusion"
should be classified as a "throwback"(or mutation).
Prof. Bell agreed to leave it out of the reports,
publishing a description in a separate paper, with no reference to the Niobrara excavations. 
In recent times, there has been new evidence that, indeed,
confirms human presence of in North America before the glacial maximum.
A recent Indian skull of apparently low type from
Nebraska. Am. J. Phys. Anthrop., XX, 5-11.
Goodyear, A. University Of South Carolina. "New Evidence Puts Man In North America 50,000 Years Ago." ScienceDaily. ScienceDaily, 18 November 2004.
Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radiocarbon Dates from Bluefish Caves, Canada,
Lauriane Bourgeon , Ariane Burke, Thomas Higham
Published: January 6, 2017
The Pleistocene Epoch is typically defined as the time period that began about 1.8 million years ago and lasted until about 11,700 years ago. The most recent Ice Age occurred then, as glaciers covered huge parts of the planet Earth.
There have been at least five documented major ice ages during the 4.6 billion years since the Earth was formed — and most likely many more before humans came on the scene about 2.3 million years ago.
The Pleistocene Epoch is the first in which Homo sapiens evolved, and by the end of the epoch humans could be found in nearly every part of the planet. The Pleistocene Epoch was the first epoch in the Quaternary Period and the sixth in the Cenozoic Era. It was followed by the current stage, called the Holocene Epoch.