THE GANGPLANK & THE TRANSCONTINENTAL RAILROAD

Next to winning the Civil War and abolishing slavery, building the first transcontinental railroad, from Omaha, Nebraska, to Sacramento, California, was the greatest achievement of the American people in the nineteenth century.   Stephen Ambrose

The Union Pacific depot at Tescott, Kansas ca. 1950.  The passenger train or Doodlebug made its last stop on 1 June 1958.  Photo courtesy of Rolling Hills Wildlife Adventure.

I have been fascinated with railroads since my childhood days in Kansas.  As a youngster I was a regular visitor to the local train depot and spent long periods of time watching the telegrapher and trying to learn Morse Code (unsuccessful).  Most warm days I would walk down to the tracks and watch the Doodlebug (Jitney) come to town.  This piece of history was an interesting two car train with the front car devoted to the diesel engine and passenger compartment (a Pullman motor car) while the second car carried mail, cream cans and other odd bits of freight.  This train, The Salina, Western and Lincoln Railroad (later purchased by Union Pacific) operated as the  Plainville Short Line going east in the morning to the larger town of Salina and returning in the afternoon heading west to its night stop.  So, one could pay a small fee and ride to the city of Salina, do some shopping/buying and return home in the late afternoon.  The morning train carried the cream cans to a creamery in Salina while the afternoon train delivered mail from a regional post office.  This was an interesting situation since one could receive two first class mail deliveries in the same day as the morning mail came by truck.  I also fooled around catching the daily freight train for a few blocks before jumping off as the speed increased.  Sometimes I rode it a little further and bailed off at a fishing hole!  While in the 6^th grade my parents let me take my first solo trip to Kansas City to watch the major league baseball game.  We got off at Union Station in Kansas City and took a bus to the old Municipal Stadium and watched the Athletics (before they moved to Oakland, CA).  I shudder today at the thought of putting a 12 year old kid on the train.  But, I survived, and times were different.

As an adult I became interested in passenger trains and have ridden Amtrak all over the U. S.  I also began reading about the history of railroading and became fascinated with the first train to span our country—the Transcontinental Railroad.  As a geology student I soon begin to realize that rocks and hills and rivers, the landforms of this country, dictated the routes of the early railroads.  The most fascinating route of all was the “Gangplank” in southeastern Wyoming.  This winter my mind became refocused on the feature, probably because I finished reading, for the second time, Stephen Ambrose’s great book about the transcontinental railroad, Nothing Like it in the World.  This tome is a wonderful description of how “geology” dictated the route of a major technological feat that linked the U. S. East with the U. S. West.  With the railway construction companies being paid by the mile of track laid, the book is an explanation of how the Union Pacific zoomed across the flat plains west of Omaha while the Central Pacific struggled going east across the Sierra Nevada Mountains.  But there is one little piece of information that is off extreme interest to geologists, and that is the September 1865 pronouncement of Grenville Dodge, of the Union Pacific, that he had found a route to cross the Black Hills (the area that is now known as the Laramie Range in southeastern Wyoming).  What Dodge described was a solution to the first major topographical problem that the Union Pacific experienced—how to get over this front range of the mighty Rocky Mountains?  The idea of a U. S. railroad linking the Atlantic to the Pacific had been debated by Congress for many years, probably at least since the 1830’s as Manifest Destiny was in full bloom.  However, then as now, senators and representatives wanted the best for their districts and states so continued to debate and propose routes.  Finally, in 1853 Congress gave the task of completing a number of railroad surveys to the U. S. Army Corps of Topographical Engineers with the results being presented back to Congress for a final decision.  Secretary of War Jefferson Davis (yes, that Jefferson Davis) assigned the Corps to investigate five routes: the Northern route (Lake Superior-Puget Sound). under the direction of Isaac Stevens, recently appointed territorial governor of Washington; the 38th-39th parallel route (St. Louis-West Coast) headed by Capt. John Gunnison (who was killed by Indians in western Colorado in June 1853. the expedition taken over by Lt. Edward G. Beckwith who completed the survey by following the 41st parallel; the 35th parallel route (Little Rock-Los Angeles), commanded by Lt. A. W. Whipple; and the 32nd parallel route explored from the west by Lt. John Parke and from the East by Capt. John Pope (Roberts, 2011). 

The western railroad surveys completed in the 1850’s by the U. S. Army Corps of Topographical Engineers. From Ostresh, 2011.

The construction of the railroad was delayed for several years due to other impending problems of the Nation—the American Civil War.  But, as soon as hostilities ended the building begin, often using recently unemployed soldiers.  The starting--ending points of the railroad had been determined:  Sacramento in the west and Council Bluffs/Omaha on the east.  However, the surveyors were still somewhat undecided as to exact routes.  At first, the Union Pacific favored following the old Oregon Trail north around the Laramie Range, up the Sweetwater River to South Pass (the easiest place to cross the Continental Divide), and then on to Utah via Fort Bridger.  But, and this is a critical but, this Oregon Trail Route was almost barren of coal until near Salt Lake City.  Wagon Trains on the Oregon Trail traveled by horses/oxen and needed forage for fuel; trains were fueled by coal.  Therefore, proximity to coal reserves was an important consideration for any route. Slightly south of the Oregon Trail route was a stage route, established by Ben Holliday, sometimes referred to as the Overland Trail. This route seemed like a good alternative since coal was more readily available in southern Wyoming.  However, there was a big problem with this proposal since the railroad would need to ascend and summit the Laramie Range, the initial front range of the Rocky Mountains.  I have written many times before about the Laramide Orogeny, that mighty tectonic event (Cretaceous into the Eocene) that created the diverse ranges of the Rocky Mountains from Utah east to the Black Hills (the “real” ones in South Dakota) and from Canada to Mexico.  The numerous ranges appeared at different times and involved both vertical uplift (often in the form of large anticlines) and faulting.  I once heard a talk by Wyoming Geologist Laureate David Love where he likened these uplifts to a bunch of hogs waking up under a blanket!  However, nature dictates that everything that goes up (orogeny) must come down (erosion) and that is what happened in the Rockies. By the late Eocene and Oligocene the tectonic uplift had stopped and the mountains had generally been worn down and were being buried in their own debris.  Adding to the sediment load was a vast amount of wind-blown volcanic ash coming in from the northwest.  Well-known formations such as the White River Group, so well-exposed in the Badlands of South Dakota, represent stream sediments shed far to the east of the mountains.  By the Miocene only a few mountain ranges in Wyoming projected above the sediment fill and by about five million years ago (end of the Miocene) a vast alluvial, sloping plain extended from the low mountain fronts eastward to at least the Missouri River (current location); we know these rocks as the Ogallala Formation.  Later, during the Pliocene, something in the earth’s crust triggered a widespread and strong uplift of the entire Rocky Mountain region.  Geologists term this as an epeirogeny—broad uplift of an entire region as opposed to “sharp” uplift, an orogeny.  When this happened streams begin to flow eastward off the mountains and the sediments were stripped off the interior basins, the mountains, and the plains to the east, especially in the areas nearest the mountains.  The modern river drainage of the Rocky Mountains and Great Plains were becoming established. 

Landscape of southern Wyoming during the Miocene with the basins filled to overflowing and many mountain ranges covered by their own eroded debris.  A long sloping plain, the Ogallala Formation extended from the ranges eastward to perhaps the Missouri River (current site).  Sketch courtesy of Wyoming Geological Survey.

 

Sketch showing current cycle of erosion that began in the Pliocene.  The basins were excavated, streams cut across mountain ranges, and the rivers of the Great Plains were established.  Much of the Ogallala Formation was eroded away and stream channels became established.  Sketch courtesy of Wyoming Geological Survey.

Today, the Laramie Range, a northern extension of the Colorado Front Range, extends from the Colorado—Wyoming state line north and west to near Casper, Wyoming. East of the mountains is a section of the Great Plains termed the Cheyenne/Denver Basin with Tertiary rocks exposed at the surface. The Paleozoic and Mesozoic rocks, mostly in the subsurface in the Basin, are upturned and eroded as they meet the Precambrian granite of the Range.  The Laramie Range, with Laramie Peak at 10,272 feet, is approximately 3000 feet higher than the rocks of the Great Plains. So, if the Union Pacific Railroad was to ascend the Laramie Range, the challenge would be to establish a route with minimal grade, minimal fill work, and a minimum number of trestles.  That route, later named the Gangplank, seemed unknown to non-Native Americans as the railroad began their westward push.  A U. S. Army Corps of Topographical Engineers project, led by Major Howard Stansbury, studied Great Salt Lake in 1849-51 (Exploration and survey of the valley of the Great Salt Lake of Utah, including a reconnaissance of a new route through the Rocky Mountains) and returned to the east via southern Wyoming and “missed” the Gangplank, although their route generally followed what was later known as the Overland Trail.  U. S. Army soldiers stationed at Camp Walback (Ostresh, 2011), a post created in 1858 to protect wagon trains crossing Cheyenne Pass on the Overland Trail, was only a few miles north of the Gangplank but no mention was made of this feature.  Nor did teamsters and travelers on the nearby Denver-Fort Laramie Trail comment on the feature.  Ostresh (2011) summed up these “missed” opportunities by stating that “while people intent on building a railroad over the Black Hills [Laramie Range] had seen the Gangplank for a period of 15 years, Dodge was the first to connect the dots and realize the potential as a rail route”. 

Sketch showing relationship of the Gangplank (Ogallala Formation) to the Laramie Range.  Adapted from Ostresh, 2011.

What is the Gangplank?  Essentially it is a piece of the Ogallala Formation that escaped erosion along the mountain front and actually extends from the Great Plains up to the summit of the granite core of the Laramie Range.  In my college geomorphology class we were told that the Gangplank is the only place along the entire Rocky Mountain Front, from Canada to Mexico, where a traveler could simply walk up a slope from the plains to a mountain summit.  As a comparison for CSMS readers in Colorado Springs, think of the Colorado Piedmont Province east of the city.  This area is quite hilly and eroded eastward to Limon while the Rampart Range front west of the city is impressive and forbidding.  If the Colorado Piedmont were similar to the Gangplank, a gentle slope of Ogallala Formation, currently exposed at Limon but absent in the Piedmont, would gently ascend to the summit of the Rampart Range!  So, Grenville Dodge traveling east and south from a foray into the Powder River Basin made a detour to explore the land near Crow Creek and Lone Tree Creek (west of current Cheyenne).  Surprised, and harassed (although it may have been Dodge doing the harassing), by a group of American Indians, Dodge and his exploratory crew dismounted and begin to walk east toward the larger remainder of his group.  Expecting to travel down the escarpment off the Laramie Range, Dodge instead found a slope that “led down to the plains without a break.  I then said to my guide that if we saved our scalps I believed we had found the crossing” (Dodge, 1910). The rest, as they say, is history as the Union Pacific passed through Cheyenne in September 1867, crested the Laramie Range at Sherman Pass (at 8640 feet, the highest point above sea level on the railroad) and reached Laramie in May 1868.  The building of the first transcontinental railroad has often been hailed as the major engineering feat in U. S. history.  However, few people know that an accidental erosional remnant helped pave the way for completion of this massive project.    
 

Looking eastward toward Cheyenne at "the Gangplank." Interstate Highway 80 and the Union Pacific Railroad follow the Gangplank from the High Plains in the distance onto the Precambrian core of the Laramie Range. Photograph courtesy of R. D. Miller, U.S. Geological Survey.

And finally, current visitors to I-80 during the winter months most likely experienced high winds and lots of drifting snow in the section west of Laramie.  According to local legend the area ranchers advised the Interstate planners to detour north around the Snowy Range and follow the route of the Union Pacific.  However, the “people from back east” plowed straight ahead and through the Range and therefore, for the foreseeable future, the highway will suffer the effects of expensive winter maintenance.  The railroad planners did know something about mountains, road grades, and winter snows. When the track got beyond Laramie, Congress removed Wyoming from Dakota Territory and gave it territorial status of its own [It became a state in 1890, the 44^th state]. At the beginning of 1877 Wyoming had fewer than a thousand white inhabitants; by early 1878, thanks to the railroad, it was estimated to have forty thousand white people [the population today (2015 census is ~ 586,000—total].    Stephen Ambrose. 

REFERENCES CITED

Dodge, G. M., 1910, How we Built the Union Pacific Railway and Other Railway Papers and Addresses: unknown publisher.

Ostresh, L., 2011, The Mystery of the Gangplank: http://picasaweb.google.com/LarryOstresh/MysteryOfTheGangplank#slideshow/5441970535271957106