by Daniel B. Botkin, originally published by Perigee Books, a division of Penguin/Putnam, 1999.

This book, originally published as “Passage of Discovery“, is an ecologist’s guide to the first half of the Lewis and Clark trail, their travels up the Missouri River from St. Louis to Three Forks, MT.  I have decided to share this book with the readers of my website, and I am going to present the entire book here, one chapter at a time, with a new chapter appearing each week.  There are more than 40 chapters.  If you follow along and read all of them, you will learn about the entire Missouri River as seen by Lewis and Clark at the beginning of the 19th century, and as I visited it during the 1990s to see what they had seen, and to learn how the countryside had changed.  Comparing what Lewis and Clark saw with what we see today is one of the best insights we can get of how nature and environment in American has changed since European settlement.   I hope you enjoy it and find it rewarding.

- Daniel B. Botkin

All of the chapters published thus far can be found in the Passage of Discovery category. Please note that they are listed in reverse order of date posted.

More books by Daniel Botkin are available for purchase from the Center For the Study Of the Environment bookstore.

20. Loess Hills State Recreation Area: To Keep A Prairie, Disturb It With Fire

There are a number of parks, preserves, and wildlife management areas in the Loess Hills of Iowa east of Onawa, Iowa.  The best way to see them is to obtain the “Loess Hills Scenic Byway” brochure from Iowa Welcome Centers by writing the Harrison County Museum Welcome Center, RR #3, Box 130A, Missouri Valley, Iowa 51555.  You can reach several of these areas as follows: From Interstate 29 take Exit 112 and go east on Route 125 through Onawa.  Just east of town take County Route L12 northeast to the Loess Hills Wildlife Management Area.  Or continue on 175 to Turin and go north to Turin Loess Hills State Preserve.  Other Loess Hills public areas can be reached from Exit 95 on Interstate 29 by going east through the town of Little Sioux on County Route F20 to Pisgah and going north or south on Route 183.

On July 16, 1804,  Lewis and Clark were near today’s Iowa-Missouri border, on the river near the present location of Peru.  Clark wrote that the river was about two miles wide, but it was not deep, because he could see snags scattered across it, and on the far shore “about 20 acres of the hill has latterly slipped into the river above a cliff of Sand Stone for about two miles.”  Looking beyond the river, Clark saw “a range of Ball [bald] Hills parrelel to the river & at from 3 to 6 miles distant from it, and extends as far up & Down as I Can See.”  He was viewing a special kind of prairie that grows on a strange and rare kind of soil, called loess.  “This prarie I call Bald pated Prarie,” Clark wrote, seemingly because the brownish color of the soil and grasses made the hills look hairless at the top.

Our modern equivalent would be to call them monk-shaved hills, because the summits are clothed in grasses, while trees and shrubs surround the bases near the water, giving the hills the rounded appearance of a monk’s head with the hair shaved above the ears.  The next day, July 17, 1804, Lewis rode out into this prairie and along a stream that passed through it, which he referred to by its Indian name,  Neesh-nah-ba-to-na Creek.  Along this stream he found “Some few trees of oake walnut & mulberry.”  The hills were not as barren as they looked; several of the men went out hunting and one of the best hunters, Drewyer, “kill’ed 3 deer, & R. Fields one,” Clark wrote.

I had long wanted to visit loess hills in a place where the prairie still existed on them, because this is a strange and unusual formation.  Waubonsie State Park, Iowa is the nearest to where Clark first walked through loess hills, but opportunities did not come up for me to go there.  My first chance came when I visited Iowa State University, and I told my hosts, Tom Jurik and David Glenn-Lewin, about my desire to visit natural areas related to the Lewis and Clark expedition.  We agreed to an exchange: lectures to their classes for a natural history tour.

From Ames, Iowa we took State Route 30 west, passing the farm town of Grand Junction and miles of farmland.  We stopped by the side of the road to look at some prairie potholes that remained in the fields.  “Best soil in the world,” David said as I took some photographs and we looked at the black, wet prairie soils still bare of crops.

As we continued on Route 30 farther west, the landscape suddenly changed.  The relatively flat land with its black soil gave way to a strangely abrupt rolling landscape of a browner and finer soil.   We had come to the loess hills, the same kind of strange, wind-formed landscape that Clark had walked on almost two hundred years before.

Loess is a material found in only a few places on the Earth; the American Midwest and China have the two largest parcels.  Loess hills are a product of the glacial ages, forming between 30,000 and 17,000 thousands years ago, created by water and wind.

Loess began as silt eroded from the Rocky Mountains by the ancient Missouri River, and by the Platte River to the south.  The faster a river flows, the heavier the material it can carry.  A mountain stream pushes boulders during storms.  Rivers separate material they carry by size, leaving the heaviest material behind near the mountains when the water first begins to slow down.  Silts are fine particles and are carried a long way downstream to where the quieter waters can no longer carry them.  As the Missouri and Platte meandered across their floodplains over the centuries, they spilled their silt wide and deep.

Toward the end of the last ice age, intense winds developed, a result of the great difference in temperatures and reflection of light between the ice and the warmer bare ground.  The great winds created silt-storms that piled the soil into steep silt-dunes.  Like sand dunes, the silt dunes formed a rolling countryside of uniform material, without any apparent layers.  Seen from the side, especially along a road cut, the soil is deep but not layered.  Here in Iowa the loess sits on top of glacial till and on top of bedrock which is much, much older.  The cliffs that Clark saw when he first viewed the loess hills were laid down in the Pennsylvanian period, more than 286 million years ago, the age of coal formation.

Two days after Lewis and Clark first saw the loess hills, Clark went for a walk on shore after a breakfast of roasted ribs of deer and a little coffee.  He began to follow fresh tracks of elk and “after assending and passing thro a narrow Strip of wood Land, Came Suddenly into an open and bound less Prarie” where trees were “confiend to the River Creeks and Small branches” and the prairie “was Covered with grass about 18 inches or 2 feet high and contained little of any thing else.”  The grass was shorter than on the tallgrass prairie that grew on other kinds of soil.  “This prospect was So Sudden & entertaining that I forgot the object of my prosute, and turned my attention to the Variety which presented themselves to my view,” he wrote.  He continued up a hill toward a “line of woods” where he found “a butifull Streem” which he followed for three miles where it flowed into the Missouri River “between 2 clifts.”  He was near the location of modern Nebraska City, probably on Table Creek.

Loess makes poorer soil than till, partially because the soil is made up of particles of one size.  The best soils in Iowa are to the east, the poorer ones along the Missouri where Lewis and Clark passed.   This was one of the things that struck Clark about his Bald-pated prairie: The grasses on these hills were sort – 18 inches – rather  than the tall grasses of the eastern prairie, some of which reached six feet.  As a result, he could get a view of a long distance, and that view was pleasing.  Reading his accounts, and driving toward the loess hills, I thought of the irony of this landscape.  It was created by ice and wind, during episodes that, people, if present, would have found terrible and destructive.  This seemingly peaceful landscape would not have been here without an environmental disaster, next to which the dust storms of the 1930s would have seemed like small dust devils.

We passed the town of Denison, Iowa, and saw a sign on Route 30 stating that we had just crossed the divide between the Mississippi and the Missouri Rivers. East of this point, all the streams flowed to the Mississippi; west, all the streams flow into the Missouri.

At the recreation area, we parked and began to walk into the short, steep, rounded loess hills.  David told me that this is an actively managed area with the goal of returning the vegetation on the hills to the way that it was before European settlement – the way Lewis and Clark saw the loess countryside.  The way to accomplish this goal was to burn.

In our century, wildfires have been considered bad – we all know the Smokey Bear advertisements of the U.S. Forest Service.  With the suppression of fire, the vegetation on the loess hills changed.   The most impressive plant we saw was eastern red cedar, a small tree that reaches 20 or so feet high.  The seeds of red cedar are eaten and excreted by birds, which spread the seeds widely.  Red cedar grows rapidly in bright sunlight, when it is not shaded by taller trees.  If the seeds fall on bare soil, they can germinate and survive. But if there is a dense cover of grasses, then the seeds land within the grass and do not reach the soil.  So there are two major intervals following a fire when red cedar can get established: soon after a fire, before the grasses are well established, and ten or twenty years later, after the grasses have matured and some of the grasses die back and expose bare soil.  Where rainfall is high enough, cedar can survive past the seedling stage and grow for forty or fifty years.  Without fire, in this eastern edge of the prairie, in locations where the rainfall is relatively high, the cedars grow well.

In the distance we could see unburned hills that were dark green from a dense cover of red cedar.   But the first hill we walked up had recently been burned to clear it of cedars and restore the prairie.  The vegetation we walked through was burned to the ground or to the low mounds of bunch grasses, except for two or third rosettes of prairie forbs that had already sprouted since the fire.  The grasses we saw included big bluestem, prairie grass, Indian grass, foxtail grass, as well as little bluestem, a prairie grass common in the East.

After we walked through the first, burnt row of hills, we could see that the unburned hills had a distinct pattern.  On the south slopes the vegetation was almost all prairie grasses, while the north slopes were heavily wooded.  As a result, when I looked south and saw only north slopes, I saw only a wooded countryside.  If I had no other view, I would have believed myself in forest land.  Then I turned and looked north and, seeing only south slopes, saw hill after hill of brown grasslands. If it had been a sunny day, I would have taken two photographs, one north and one south, and could have shown it to my friends and made them believe they were from two completely different areas.  It was the clearest illustration of the effect of the direction that a hillslope faces on its vegetation.  A south-facing slope in the northern hemisphere gets sun most of the day, and sun dries out the soil.  A north-facing slope is shaded a good part of the day, stays cooler and retains its moisture.  The steep, short hills formed by loess accentuated these differences in this transitional countryside.

The drier south-facing slope is more likely to burn.  In this country, a south slope was like landscape far to the west, while a north slope was like land to the east, because the entire prairie land is in the rain shadow of the Rocky Mountains.  The average rainfall is lowest just east of the Rockies – in the high plains 100 miles east of Denver, for example, it averages 12 to 16 inches a year.  Then rainfall increases eastward, 20 inches per year at Dodge City, 28 inches near Lincoln, Nebraska, 36 inches east of Kansas City.

We walked through these steep, strange hills for several hours.  It was a satisfying day in spite of the clouds and drizzle; we had seen one of the stranger but pleasing landscapes of the Missouri River drainage, saw constructive activities to restore the large natural area to the way Lewis and Clark had seen it, saw the effects of ancient glacial and river events on the modern landscape and smelled the sweet and sharp scents of prairie plants.  I had learned, paradoxically, that the countryside Clark found “Sudden & entertaining” to the point that he forgot what else he was doing, was the product of cataclysmic forces of fire, ice and winds.