"Barren Buttes" by NPS/Mark Meyers , public domain
Coal Vein Trail
Brochure for the Coal Vein - A Guided Nature Trail - at Theodore Roosevelt National Park (NP)int North Dakota. Published by the National Park Service (NPS).
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National Park Service U.S. Department of the Interior Theodore Roosevelt National Park Coal Vein A Guided Nature Trail Hel p res us sav our e Plea ces the se retu ! rn bo xw hen this bro ch you Wa fnis ure to nt h hi See a cop y? D king bac kp . age ownlo ad for it! det ails . Be aware of the following: Cliff Edges Stairs Rattlesnakes Wildlife Poison Ivy Beautiful layers of rock tell a story of the 60-million-year geologic history of the badlands. From ancient swamps to recent coal fres, this landscape is constantly changing. Learn about badlands geology by following the numbered trail posts. Stay to the left to follow the posts in numerical order. 1. Layers Each layer of rock has its own origin story, told by its color. Brick-red Clinker forms when coal veins catch fre and bake the rock above, changing it into this much harder, red rock. Black Coal is the remains of ancient plants and animals that lived in Evergladeslike swamps. Brown and Tan Sandstone, siltstone, and mudstone are sediments washed down from the Rocky Mountains. Blue-grey Bentonite clay is made of ash from distant volcanoes. 2. Collapse In this area there was a 12-foot-thick coal vein deep underground. In 1951 it caught fre and burned for 26 years. As it burned away, the rocks above were left unsupported and the surface collapsed, forming the depression you are about to enter. Before the fre, the land was level with the top of the stairs. 3. Bentonite Notice the sediment on either side of the trail. Fifty-fve million years ago, volcanoes in the Rockies spewed out ash that blew east. At that time, this area was a vast, tropical swamp. The ash settled in wet areas and became bentonite clay. Bentonite looks like popcorn when dry (below), but becomes sticky, slick mud when wet. It can absorb up to fve times its weight in water. Known as the mineral of one thousand uses, it is used to seal landflls and ponds, to make cat litter, and much more. Stay to the left to continue on the guided nature trail. Take the right on the cutoff trail to avoid a section of trail with very steep stairs. You will rejoin the guided nature trail near post #11. 4. Caprocks Rocks in the badlands are generally soft and easily eroded by rain and streams. Some are harder than others, and become caprocks. A caprock acts like a helmet, shielding softer rock underneath. When the rocks underneath fnally erode away, large pieces of caprock break of and fall. The large pieces of sandstone behind you were once caprocks at the top of the hill. Left: An example of a caprock found elsewhere in the park. 5. Dry Climate The dry climate of western North Dakota keeps the badlands from eroding away more quickly — if rain were more common, the soft rocks would have washed away long ago. The lack of moisture allows only the hardiest plants to survive. The trees here are Rocky Mountain juniper. They, and all the other shrubs, grasses, and wildfowers you fnd here, are adapted to survive in this land of extreme temperatures and little moisture. 6. Seasonal Pool Low spots like this one formed when the ground collapsed during the coal vein fre. They fll with water in the wet springtime and after summer rains. These seasonal ponds are important 7. Burn Out Just ahead and to the right is where the coal vein fre burned out after 26 years (1951-1977). Visitors could see smoke, glowing coals, and sometimes fames. They even roasted marshmallows over the fre! Right: This photograph was taken in the 1970s as the burning coal fre crept toward its end. Caution! Steep cliff edges ahead. habitats for western chorus frogs which must lay their eggs in standing water. Listen for the chirping of the male chorus frogs near seasonal pools from April to June. 8. Hills Overlook The trail goes to the right. To your left is an overlook. Be careful; the edge drops of sharply. From the overlook, you can see how the terrain afects plant life. The slopes you see face north. They receive very little direct sunlight which helps retain moisture, allowing juniper to thrive. South-facing slopes receive a lot of direct sunlight. They are very dry and support only hardy grasses and a few drought-tolerant shrubs. 9. Clinker Feel the red rock next to the post. It is locally called scoria, but its true name is clinker. Clinker is created when a burning coal seam bakes the rock layer above it. Baking rock is like putting clay into a kiln to make pottery — the rock hardens as it bakes. Because clinker is one of the hardest rocks in the badlands, it functions as a caprock atop many buttes. 10. Seasonal Stream Just ahead, stairs lead to the valley of a seasonal stream. As you descend, notice the cool, moist air against your skin. Because it is protected from the sun, this area stays moist and cool. Note the plants you see here and compare them to the plants you have encountered in open grassland. What are the diferences? Continue straight ahead to follow the guided nature trail. 11. Ignition This is the spot where the coal vein ignited during a lightning storm in 1951. Even today, these natural fres Caution! Steep cliff edges ahead. can be started by lightning, prairie fres, or even spontaneous combustion. 12. Clinker Overlook The small spur trail going up the hill leads to an overlook. Be careful; the edge drops sharply. When you look to the left and right you can see and feel the clinker where it forms a protective caprock. The red color of the clinker comes from iron in the rocks that has oxidized (rusted). 13. Slumping The hill in front of you has the appearance of sliding slowly into a jumble. That is exactly what it is doing through a process called slumping. When the coal vein burned under this area, cracks formed in the hillside. Rain fowing into the cracks weakens the hill, especially where it saturates bentonite clay layers which become slippery when wet. As the bentonite slides, the hill slowly slumps away. Slumping happens on a small scale like you see here, but also on a very large scale when entire hillsides slide. The picture below, taken in the North Unit, shows masses of rock that slid from near the top of the canyon, coming to rest far below. June 1958 14. Grassland When the underground coal fre was burning, this area looked more like a wasteland than a grassland. After the fre burned out, prairie plants reclaimed the land slowly over time. From a distance, prairie may look plain, but it is actually one of the most diverse ecosystems in the world. An up-close look reveals many diferent species of grasses and other plants. 15. The Big Picture Take in the view. The things you have observed on this trail are not unique to this one spot. They can be seen, felt, and identifed throughout the badlands. Even today, coal fres shape the dynamic landscape of the badlands. Geology is not only a study of the past; here it is an ever present process. How do these things ft into the big picture of the park? How long will these processes continue to shape this land? 16. Chimney What is unusual about the massive piece of clinker in front of you? Fires need oxygen, even when they are burning underground. As the coal fre burned deep into the hillside, cracks in the rock layers allowed air to be sucked down into the fre. Fire burned up the cracks and baked the rocks nearby forming vertical “chimneys.” Chimneys are the hottest part of the coal fre and bake the rock inside into a very hard clinker called porcellanite which is especially resistant to erosion. This chimney you are looking at was exposed when softer sediments around it eroded away. There are many signs that large coal vein fres have burned throughout the park in the past. Even today, coal fres can sometimes be found shaping and changing the landscape of the badlands. Geology is not only a study of the past; it is an ongoing process. We hope you enjoyed your hiking experience. Please return this brochure to the box at the beginning of the trail. Thank you! This trail brochure was written and produced by the rangers of Theodore Roosevelt National Park. It was printed using your fee dollars. Thank you for your support! EXPERIENCE YOUR AMERICA™