The Dig Shelter sits atop an open fossil quarry on the eastern side of Waco Mammoth National Monument. The Dig Shelter is approximately 75 feet wide and 110 feet long totaling 8,350 square feet. This large building was designed for both protection and beauty, with a modern architectural style and mixed material construction. The building is supported by 12 steel beams in concrete piers that rest on bedrock. The steel beams are connected by concrete walls extending into the earth to a depth of about 10 feet, which prevents water from seeping into the structure or sediment. These concrete and grey metal walls support the building’s sloping roof featuring a drop ceiling. The roof is cantilevered over the porch at the entrance with a large, triangular window between the porch and the shelter’s steeply angled roof. This angle and treated windows and doors protect the fossils inside from ultraviolet light.
To reach the Shelter, guests cross a footbridge of metal grate and concrete. A ravine about 10 feet deep runs below the bridge. Many trees grow on the hills around the ravine, but the ravine itself is covered in grass. Sixteen different Columbian mammoths, all females and their young, were found in that ravine, seemingly huddled together. Once across the bridge, guests enter the Shelter through a pair of glass doors.
A walkway is suspended from the ceiling, so it does not touch the quarry below, and the fossils are protected from vibrations of people’s footsteps. The Dig Shelter has no floor, instead covering the excavation site like a cap. Ambient light fills the room, and the climate is maintained at a steady 70 degrees Fahrenheit year-round.
A mural of a lone bull mammoth is on the right wall as guests enter the building. This depicts mammoth “Q”, the only bull mammoth that has been found at the site so far. The bull stands at a height of 13 ½ feet and is viewed from the right side. The mural of “Q” faces the door as if to greet guests, and it is in a walking pose with the front left leg raised. The mammoth has beautifully curved tusks, like its elephant relatives. The artist painted Mammoth Q’s hair in a mixture of browns, reds, and golds. The hair is longer on the top of the head and back and resembles thick curly animal fur. The ears are about the size of dinner plates. The trunk extends from the upper lip, between the tusks, and then down to almost touch the ground. Scientists are unsure of the actual size of Columbian mammoths’ ears and trunks, nor do they know the true color of these animals. These are all educated guesses the artist has made because scientists have not recovered soft tissue from Columbian mammoth fossils.
Another mural of a nursery herd, or female mammoths and their young, covers the south wall of the Shelter, which is left of the entrance. This mural illustrates the sixteen mammoths that scientists found in the ravine outside the Shelter. Thirteen of those were adults, and three were calves. The mural depicts this herd moving through a ravine away from a rushing river, which also includes a camel being swept away. The adults, all female, have tusks that are shorter and less curvy than a male’s tusks. The females surround a calf, positioned between the calf and the water. The calf, which is at the center of the mural, is sculpted and extends out from the painting. A few scattered trees dot a tall grass prairie. Although mammoths lived all over North America during the Ice Age, or Pleistocene Epoch, the temperatures were moderate in this area.
The walkway extends north before curving left, leading guests over the quarry below, and ending at a platform on the west wall of the Shelter. An 8-foot-long replica mammoth skull with tusks sits on display at the north side of the platform. On the south side of the platform sits a small, wall-less laboratory. This area is a workspace for fossil preparation, which includes removing fossils from sediment, stabilizing fragile material, and repairing damage so fossils are ready for study and display. Two lab tables hold an assortment of picks, brushes, and other delicate tools, as well as mammoth rib fossils currently being prepared. A large, waist-high bin containing sand sits to one side. This sand box is used to hold fossils upright while glue dries. Black metal shelving lines the west wall. Replica skulls of sabertooth cats, a camel, and a beaver sit on the top shelf. The lower shelves hold turtle and camel fossils sorted onto green trays, as well as vials of glue and additional tools.
The murals, walkway, and lab all sit high above the quarry, which fills the entire center of the Shelter. As you look down from the walkway to the quarry below, vegetation has been cleared, exposing a crumbly, tan and reddish clay. The quarry is a large pit that extends straight down into a sloped hillside, and fossil bones are exposed in two levels. Undisturbed columns of sediment, called pedestals, rise from the lowest level. The top of each pedestal preserves the original surface of the hill, allowing guests to see how deep scientists have dug.
In the lowest level of the quarry, currently 9 feet below the walkway, a nearly complete skeleton of a juvenile mammoth lies on its side. The fossil bones are dry and noticeably fragile, often cracking where the clay cracks. A neat row of vertebrae connects to a ribcage. The bones of the legs are pulled up to the ribs, making the fossil appear to be in a fetal position.
A skeleton of a Western camel lies ten feet north of the juvenile mammoth. The two back legs are crossed, one over the other, near the bowl-shaped pelvis. A front leg is nearby—its foot ending with two long toes. The skull and jawbone sit to one side, cradled by a protective white casing that surrounds the fossils on all sides but the top. Scientists call this casing a plaster jacket, because it is made of burlap and plaster of Paris. Whenever possible, scientists do not move the fossils from the place where they were buried. They only jacket and move a fossil if it is in danger of deteriorating.
Both the juvenile mammoth and Western camel are in the lowest level. Sixteen mammoths were found at this same depth in an earlier excavation, less than a hundred feet away. Scientists think the animals at this depth all died together and were buried approximately 68,000 to 65,000 years ago. All the mammoths in this lower level are adult females or juveniles—the first nursery herd of Columbian mammoths ever found in North America.
A tall pedestal rises north of the camel, and temporary stairsteps have been carved into the clay next to it. These steps connect the upper and lower levels of fossils. The skeleton of an adult female mammoth, named Mammoth W, lies on its side at the northernmost edge of the upper level. A well-preserved pelvis with a somewhat diamond-shaped opening helped scientists identify this mammoth as a female. A line of vertebrae connects the pelvis to the skull. The vertebrae closest to the skull have long, bony extensions. When the mammoth was alive, these extensions, called processes, pointed upright and supported a mass of muscle behind the mammoth’s neck. Over time, this mammoth’s skull collapsed under the weight of the sediment that buried it, but the cheekbone and the two upper teeth are intact. Each tooth is long but narrow, with parallel ridges that make the surface of the tooth resemble the tread on the sole of a shoe. Tusks grew from sockets called alveoli, located at the front of the skull. Scientists removed most of her right tusk for preservation, but the root is visible inside the alveolus. On close inspection, the root is made of concentric rings of fossil ivory, which is white and chalky to the touch.
Southwest of female mammoth W, the upper level of the quarry also contains five fossil rib bones from a smaller animal. These ribs were found near the tooth of a juvenile sabertooth cat, but scientists have not yet identified the type of animal that left these ribs behind. The cat tooth is one of the few fossils removed from the quarry, and so a replica sits in its place. The tooth, roughly three inches long, is flat and blade-like. Only one inch of the tooth is covered in enamel. The remaining two inches are the root of the tooth. Both edges of the enamel have fine serrations, much like a knife.
The remains of three more mammoths are on the eastern rim of the upper level of the quarry. Moving north to south, guests see the forelimb bones of an adult mammoth, the leg bones and shoulder blade of a juvenile mammoth, and the nearly complete skeleton of an adult male mammoth, Mammoth Q, also depicted in the first described mural.
Mammoth Q lies in the upper level of the quarry, about 18 inches to two feet above the lower level. The skull of Mammoth Q, in-situ, points north and sports the longest pair of tusks found at the site. Each tusk is eleven feet long, curving outward and then back in, so that the tusks cross over each other slightly at the tips. The skull has collapsed, with a round, bowl-like impression visible on top. The skeleton is laid out as though mammoth Q laid down on his stomach. His right front leg bones stretch forward, while the left front leg bones stretch back and are trapped beneath the right side of his rib cage. One of the rib bones on Mammoth Q’s left side has a growth about the size of a baseball. This growth is evidence that mammoth Q was healing from an injury prior to the time of his death. The male’s two back legs, still connected to the pelvis, stretch out behind his body. Q’s right rear leg is incomplete - a femur with no lower limb bones attached. The patella, or kneecap, sits nearby. The patella has visible bite marks around its edges, perhaps a clue to an ancient meal.
Only one third of the land now covered by the Dig Shelter has been excavated and less than one acre of land outside of the Dig Shelter was excavated. The fossils of at more than 20 mammoths, a couple of camels, a saber-toothed cat, and several other animals have been recorded in this relatively small area. The potential for more discoveries in unexcavated areas of Waco Mammoth National Monument inspires us to explore, appreciate, and ponder the mystery and diversity of life on Earth.
Guided, audio-described virtual tour through the Dig Shelter at Waco Mammoth National Monument. The only sound is a description of the rooms with basic context of what you see. The transcript is available below.
9 minutes, 53 seconds
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