Friday June 6, 2014, 69 miles (112 km) – Total so far: 925 miles (1,488 km)
It’s going to be a rockin’ day – all sorts of geology and paleontology to check out today, let’s go!
A mosasaur fossil was found high up on a hill in Pierre shale at Niobrara State Park in 1986. While building a park road, this sea serpent (around 33 feet long with paddle fins and a big-ass head with 3-4 inch-long teeth) was unearthed. The excavation site is marked along one of the roads by the cabins. We saw the actual fossil when we visited Morrill Hall in Lincoln last year. Getting my mind in fossil mode is a great start to the day!
Our next geology feature for the day comes as we fly down off the hill from the park. We cross the Niobrara River – only the Niobrara River now flows mostly down the western channel called the “Mormon Canal”. The flow is fast and remarkably clear as we ride over the canal bridge. But when we get to the bridge with the sign “Niobrara River”, there is no water flowing underneath.
It is a bit peculiar, but it is testament to the dynamism of river flows. When Gavins Point Dam was built downstream on the Missouri River, it caused river levels to rise upstream. The Niobrara River, in response, built up sediment in its lower reaches (up to 7.5 feet in places by 1996). The rise in the riverbed level caused shifts in the channels and problems with flooding. Now the Niobrara has largely abandoned its eastern channel – the river – and flows in the ‘canal’, except in times of flood. Floods are more frequent now, however; a flood in 1960 took out the road bridge and wiped out the state park, which has since moved to higher ground.
We turn off on Highway 14 to follow the Niobrara upstream. It is very scenic – in a way you might not associate with Nebraska. The river is deeply entrenched and hosts a healthy-looking riverine environment of tall, lush trees, long grasses and reeds, and areas of wetlands. Kermit’s family members call out from the swampy ground. Flashes of silvery water can be seen between the trees and mid-story bushes when the river meanders close to the road. Grassy hills rise behind.
Now take your mind back to the Cretaceous Period when the Pierre shale was being deposited in the Western Interior Seaway between 70 and 80 million years ago. The part of Nebraska we are in now was at the bottom of the seaway. The Pierre shale we see today was the muddy, oxygen-poor floor of the sea that collected all the debris of life from the oxygen-rich waters above. This type of rock was being deposited in a huge area on top of all that Niobrara chalk we saw yesterday, including all along the Front Range of the Rockies in Colorado and up into South Dakota and the Black Hills. Different layers of the rock have lots of fossils; other layers have lots of concretions (harder areas of rock, sometimes oblong or spherical, encased within the shale); many layers have lighter bands from deposits of volcanic ash.
Now, come back to the present day. The road we are riding on is freshly paved in places, often where the bends of the river sweep close to the road. This is because the road keeps slipping away and sliding downhill. The Pierre shale lies underneath more recent sediments, and that 70-million-year-old rock is prone to landslips and slumps because it cannot maintain a slope greater than 10 degrees. All that volcanic ash in the rock layers forms a very weak and unstable clay. The river keeps undercutting the shale at the base of earlier slides, causing further movement. Apparently, the road had to be rerouted in 1994 because of the slides, and based on this brand new pavement, the rerouting isn’t all that stable either! Knox County, where we are, has more than 40 documented places where landslips impact roads.
This is one of the things I love so much about geology – something that happened millions and millions of years ago in an environment so totally opposite to today can impact life in this very moment. If that doesn’t give you a sense of connection to life and history on grand scales of time, I don’t know what could. Oh, I do know – the Ashfall Fossil Beds, where we are heading now!
First, we need a snack break in Verdigre. The town lies along Verdigre Creek – a deep, clear creek with lots of shade that leads to the main street. Several of the locals give me alarmed looks. When I stop at the grocery, I find out why. They think I’m with BRAN (Nebraska’s version of RAGBRAI). This town is a stop on their ride in a few days time. The locals think I’m part of the group – and they aren’t quite ready yet!
Verdigre is a neat little place – and full of Czech everything. They take a lot of pride in the town’s Czech heritage. They also bill themselves as the Kolach Capital of the World. What this means for me is that I can get pastries at the bakery that remind me of visiting my Ukrainian relatives in childhood (many of the Eastern European countries have very similar foods – they just call the dishes different names). Oh yum, yum, yum! What a nice change in taste in the constant pursuit of calories.
From Verdigre, we have many hills to climb and descend. Once we turn west on 872nd St, the hills get even steeper. All of these climbs and descents take us in and out of the creek and its tributaries. They have carved a very rugged topography of ravines and valleys out of a once fairly flat surface. Have a look on Google earth or satellite of this area (go ahead, it’s good nerdy fun!) and you’ll see all the auxiliary veins of ravines branching out from the main creek like a big deciduous leaf. Up and down we go through a bunch of them.
From our last crossing of Verdigre Creek, there is a steep climb up to the visitor’s centre at Ashfall Fossil Beds. Grunt your way up and prepare to be amazed!
About 12 million years ago, the hot spot now under Yellowstone was positioned under southwest Idaho. An eruption of nearly incomprehensible size spewed volcanic ash over much of the present western U.S. Ash up to a foot deep covered much of Nebraska. Winds blew the ash off of high points and settled in low points, such as waterholes, up to eight feet deep.
At the time, Nebraska had pockets of jungle and vast areas of grasslands. Flora and fauna were diverse, including horses, rhinos, camels, deer, dogs and ancient elephants. When the ash reached the waterhole where the fossils are found, the animals did not die immediately like a Nebraskan Pompeii. Instead, they slowly choked to death. The volcanic ash clogged the lungs and the animals died over a period of days to weeks. Small animals, such as turtles are found at the bottom of the lake, and likely died first. Larger animals died later. Nearly every fossil found here has abnormal bone growths associated with asphyxiation due to severe lung disease.
Over 200 fossil skeletons have been found, including: five species of horses, three species of camels, three species of dogs, the barrel-bodied rhino, turtles, the giant tortoise, deer and several species of birds. The animals are preserved exactly how they died – they have even found fossilized food in their mouths and stomachs. One rhino still has her fetus preserved inside. Adult rhinos have been found with, presumably, their calves.
What makes this site so incredibly amazing is that all of the skeletons are left as they were found. It is as if you are standing there 12 million years ago in the final moments of these animals’ lives. The detail in the fossils is awe-inspiring. In some places, you can also see their final footprints! They have evidence of some animals being scavenged – gnaw-marks on the bones and pieces of skeletons dragged several feet from the rest of the body. One rhino has separated ribs – a result of the gases escaping his body as he died.
The information gleaned from this site has also helped scientists better understand horse evolution and show that it was more complex than a linear progression from three-toed to one-toed. Oh, I could go on and on about the significance of this place!
I first check out the visitor centre displays. After getting a good overview of the event, and how Prof Voorhies first found the site and began excavations, I head down to the rhino barn. The large building is built over part of the deposit. As you walk there, you see the flag sticking up that shows where the first skull was found in 1971.
Wow! Wow! The detail and the positions of the animals in relation to one another just floors me. There is information along the boardwalk that identifies the skeletons and provides interesting facts about each one. I chat to young Ethan, a student palaeontologist who will be starting grad school at Duke in the fall, about the size of the deposit and how much more they expect to uncover. I ask him what he is currently working on – he is uncovering a turtle and a plant.
As I make my way around, trying to get my head around the significance of this place, I see an older man in baggy jeans and an old white undershirt walk into the building. I swear he has a rope holding up his jeans. He looks like someone who would be begging on a street corner, but this is Prof Voorhies!! I’m star-struck. There are a million questions I’d love to ask him – what did he feel like when he realized how huge the deposit was? How hard was it to convince the funding bodies of the site’s significance? If I were an out-going extrovert, I’d say, “So I met Ed Berogie back at Ponca State Park and he told me I had to come here, say hello and see your amazing finds”, and then go from there. But I am not a networking extrovert, so I don’t.
I spend way too much time in there just feeling so incredibly connected to all of time and the millions of years of deposition and erosion that has led to this find and me being here in the building today. Life is so incredibly huge! I am the luckiest chick in the world today to be here looking at these exquisitely preserved fossil skeletons.
I spend some time just looking at the context of the find and trying to imagine the area as a waterhole in a grassland instead of an eroded creek headwall in a grassland. I imagine the camels and the rhinos and the giant tortoises ambling across a landscape a bit lusher than this one. I have a snack while gazing out over the site. I just can’t believe it’s not more well-known and that there aren’t hundreds of people here on any day (there are about four other families and one school group there while I am).
Soon enough, it is time to go. We need to get going if we are to beat the afternoon storms to O’Neill. I decide to head down to Hwy 20 instead of heading back up to the county road I came in on. I’m hoping Hwy 20, even though it is a few miles longer, will not be as crazily hilly as the county road.
My gamble is rewarded with very fresh and smooth pavement on Hwy 20 to Orchard. The shoulder is wide and once I get to the junction with Hwy 275, the wind is a bit behind me. The combination of the bit of a push, the flat terrain, and all of the nerdy energy surging through me from the Ashfall visit, has me pushing 22 mph. I am just pumping hard and feeling so incredibly happy and alive.
I’m also trying to beat developing storms to O’Neill. I can see the sky getting darker ahead of me. The valley of the Elkhorn River is wide and supports many crops. The creek running through the valley is undersized compared to the size of the floodplain. The geologists theorize that the Niobrara River, only 15 miles away at one location, has captured the upper drainage of the Elkhorn as the Niobrara’s tributaries have cut back into the Elkhorn drainage in the past 5,000 years. This has deprived the lower section of the Elkhorn some of its water, and now there is a creek where there used to be a river.
Yes, I’m pounding out the miles, spurred on with the energy from viewing geology from 70 million-years-ago, 12-million-years ago and 5,000 years-ago and revelling in its intersection with the present. If you can pedal out a grin, I spun out a huge one.
The sky is quite dark by the time I get to O’Neill. Areas west of town get rain and hail. Nothing makes it to O’Neill, though. I celebrate an absolutely amazing day with a Smores Blizzard at Dairy Queen. Geology may not be the flavour of the month, but for the nerdy in taste, the wonders of millions of years earth’s history is the most amazing treat.