SUPERIOR, Nebraska (STPNS) -- Tuesday, Steven Holen, curator of archaeology, Denver Museum of Nature and Science drove to one of his favorite digging sites - Lovewell Lake. The high spring inflow eroded the shoreline enough to expose the bones of mammoth which lived in the area 13,000 years ago.

Cody Newton, an intern working on his doctorate degree at the University of Colorado accompanied Holen.

One dug out and cast a mammoth ulna (the large bone of the front leg). The other dug out a portion of the mammoth's jaw bone, tooth and two ribs. After casting the bones were transported to Colorado for study. Holen expects they will eventually return to the University of Kansas.

Holen was raised near Overton, along the Platte River. "It was fairly common on our farm to find mammoth bones and Indian artifacts," Holen said. "Sometimes when I was driving a tractor in the field, I would spot an artifact, get off the tractor to pick it up and keep looking until I would find myself 30 or 40 feet away from the tractor. I have always been fascinated by such. When I was 15, dad told a neighbor I should become an archeologist because I certainly was not going to make farmer."

Holen studied at the University of Kansas. A part of his schooling there involved digging at Lovewell Lake. Holen has since served on the K. U. faculty and has also worked at Nebraska's state museum.

The ulna he found Tuesday appeared to be intact. It was approximately 30 inches long and five to six inches in diameter at the thinnest point.

Holen projected the mammoth to be between 26 and 28 years old when it died of natural causes.

"Mammoths live to be 50 to 60 years old. This would have been a Colombian Mammoth with minimum hair. Age is determined by its teeth. The mammoth is a cousin to the modern day elephant. They had six sets of teeth during their life time. Two large teeth in the front on each side of their mouth which they used to grind the plants they ate. New teeth grew behind and pushed out the front teeth as they wore down.

"A mammoth could eat several hundred pounds of grass each day. The male mammoth weighed four to five tons and stood 13 feet high at the shoulder," he said.

"From bones dug in the Lovewell Lake area, there is evidence of human involvement by modern man 19,000 years ago," he continued. "That is controversial, because some think there were not people here at that time."

Holen estimated the mammoth bones dug this week are 13,000 years old and based on bones previously dug at the site, probable from the same animal.

"Most of the bones dug here have enough protein and collagen to carbon date them," he continued.

"There was a dramatic climate change 13,000 years ago in this area. It happened rapidly, the seasons became more pronounced: the winter colder and the summer hotter. Prior to the climate change, the growing season was longer and the winter and summer mild. It was a more equitable climate

"There is evidence the caribou came this far south. Other animals from the north that like cold lived here and animals from the south that like heat aksi lived here.

"There are two theories why most of the horse, camel, dire wolf and mammoths bones we find in this area date to 13,000 years ago. One theory is humans over hunted. But if that were true, why did the bison survive?

"I think the animals could no longer survive here with the climate change," Holen said.

Holen has published some of his findings from the Lovewell area and the White Rock creek in international journals. The area is one of his favorite excavation sites. Based on his findings, he believes the White Rock creek provided a dependable source of water, even during times of drought and the area had trees 13,000 years ago.