250.5 YUMA station, 281 S. Gila Street. Elevation approximately 139 ft. Yuma is the county seat of Yuma County. Following the establishment of Fort Yuma, in 1858, two towns sprang up one mile downriver from the Fort. The town on the California side was called Jaeger City, named after the owner of Jaeger's Ferry that crossed the river there. The other town was called Colorado City, a land speculation by Charles Poston and site of the custom house, which sprang up on the south side of the Colorado River in what is now Arizona, but at that time was just north of the border between Sonora, Mexico and California. After the Gadsden Purchase it bordered on the Territory of New Mexico, that became the Territory of Arizona in 1863. The Colorado City site at the time was duly registered in San Diego, demonstrating that both banks of the Colorado River just below its confluence with the Gila were recognized as being within the jurisdiction of California.
After the California Gold Rush, during the 1870’s, the Yuma Crossing of the Colorado River, which was much narrower than most Colorado River crossings, was the site of ferry crossings for the Southern Immigrant Trail. In 1877, the bridge over the Colorado River was constructed by the Southern Pacific Railroad. Prior to that time, the former Colorado City was a major steamboat stop for ships traveling up the Colorado River. In 1864, the Yuma Quartermaster Depot was a major supply point for many settlements in the area.
Yuma is the home of Yuma Crossing State Historic Park, Yuma Quartermaster Depot State Historic Park, the Yuma Territorial Prison State Historic Park (see MP 250 above), the Imperial National Wildlife Refuge, and the Sanguinetti House Museum and Gardens, which was the home of pioneer merchant E.F. Sanguinetti. In addition, Yuma holds an annual Rodeo and County Fair.
Between here and the Yuma Mountains, we will be crossing the Yuma Desert, a very dry valley which is sustained for agricultural use by irrigation from the Colorado River, except in its extreme southern part.
We are now crossing the Sonoran Desert subprovince of the Basin & Range physiographic province. The Sonoran Desert is generally at a higher elevation than the Salton Trough section we have traversed in California. In addition, the mountain ranges are somewhat lower and less distinctive, as most of the subprovince is characterized by intermountain basins and alluvial pediments. The rocks in the cores of the Sonoran Desert mountain ranges are generally Precambrian in age.
252 Across the highway on the left (eastbound) can be seen the edge of the Colorado River flood plain.
256 Approximately 2 miles north of the railroad, the Gila River flows into the Colorado River. The flat area across the highway on the left (eastbound) is the floodplain of the Gila River here.
259 Pass beneath Interstate 8. North of the railroad (left if eastbound) appear to be two newer high-density communities, College Park and Tamarack (not shown on accompanying topographic maps)
Atop the mesa beyond the new developments listed above, on the left (eastbound), is Arizona Western College, a public community college which offers occupational certificates or Associate’s Degrees in 98 academic areas. It is one of the few community colleges in the Nation that offers on-campus housing for students.
261 Cross the Gila Gravity Main Canal here. Note the pump station on the left (eastbound). Water is pumped from adjacent canals into the Gila Gravity Main here for agricultural irrigation.
262 Pass the former site of Fortuna, named after a nearby mine. South of the railroad is Fortuna Foothills, a group of several residential subdivisions.
264 Pass through Blaisdell, named after Hiram W. Blaisdell, who was Chief Engineer of the Mohawk Canal Company. The community was established in 1896.
On the right (eastbound) is the U.S. Army’s Yuma Proving Ground, a large military facility which conducts tests on nearly every weapon system in the ground combat arsenal.
On the right (eastbound) are the Gila Mountains, a fault-block range composed of Jurassic-aged (150 to 200 million years old) granitic intrusive rocks, primarily granite and diorite. The southern part of the range (behind railroad on the right) is composed of Precambrian-aged metamorphic rocks, primarily schist and gneiss of Early Proterozoic (2500 million years before present) age.
(note: the Precambrian Era generally refers to the geologic time span from the origin of the earth (some 5000+ million years ago) until the beginning of the Paleozoic Era, approximately 570 million years ago. In general, the Precambrian was a time of ”no life,” and, as generally indicated by the vast majority of geologic research, plant and animal life as we know it, evolved near the beginning of the Paleozoic Era. Since the “Precambrian” encompasses such a very very long time span, geologists have generally divided the Precambrian into the Archean (5000 to 2500 million years before present) and Proterozoic (2500 to 570million years ago) Eras. In this route guide, the terms Archean and Proterozoic will be used when possible; otherwise, the general term “Precambrian” will be used.)
268 As we travel around the northern tip of the Gila Mountains, the rocks exposed on the right (eastbound) closest to the railroad are Oligocene- to Miocene-aged (36 to 5 million years old) sedimentary rocks. Partway up the slope, barely visible from the railroad in the distance, is a normal fault in which the upthrown block (furthest upslope) consists of older, Paleozoic-aged (570 to 250 million years old) sedimentary rocks, which now lie against the much younger Oligocene- to Miocene-aged rocks (closer to the railroad) on the downthrown block of the fault.
The Wellton-Mohawk Canal is adjacent to the railroad on the left; the Gila River (normally dry) is visible immediately behind the irrigation canal.
We are also following the former route of the Butterfield Overland Mail stagecoach, which is adjacent to the railroad on the left (eastbound).
271 Pass through the ghost town of Dome, which was named after nearby Castle Dome Mountain. It is unclear from the available references whether Castle Dome Mountain is the same as the Gila Mountains. Dome was first established in 1858, along the Butterfield Overland Mail stagecoach route. Most of the town was then washed away during the Great Flood of 1862, but several years later, in 1892, the community was re-established. This was a center of placer gold mining activity during the latter part of the 19th Century.
On the left is Dome Valley, and across the valley are the Muggins Mountains, which are of similar geologic structure as the Gila Mountains.
272.5 Jurassic-aged granitic and dioritic intrusive igneous rocks form the bluffs on the right (eastbound). Wellton-Mohawk Canal and Gila River are visible on the left, along with the route of the Butterfield Overland Mail.
278 Pass through Ligurta and cross over old Highway 80. The Wellton-Mohawk Canal and Gila River are visible on the left (eastbound). Some fossil horse bones have been found in this area in the Pleistocene-aged deposits along the Gila River.
279.5 Cross the Wellton-Mohawk Canal.
282-283 The community of Ligurta Foothills is visible on the left (eastbound – not shown on accompanying topographic maps). The Muggins Mountains are visible to the north (left if eastbound – see MP 271 above). We are crossing the Mohawk Valley.
286-288 Pass through Wellton, a popular retirement community. The town was originally called Adonde, and was a station one the Butterfield Overland Mail stagecoach route. The name Wellton came from some deep water wells which were drilled here by the Southern Pacific Railroad. The town was established in 1904.
288.5 The track which diverges from this track here on the left (eastbound) was the former route of theSunset Ltd, when the route passed through Phoenix.
290 We are now paralleling Interstate 8 on the right (eastbound).
293.5 Cross Mohawk Canal, used for irrigation.
295 The prominent hill on the left (eastbound) is Antelope Hill. It is composed of Oligocene- to Miocene-aged sedimentary rocks, and was formerly quarried for sandstone. Reportedly, petroglyphs from ancient civilizations have also been found in this area.
298-299 Pass through Tacna. Note small landing strip on the right (eastbound). Tacna was originally located a few miles west at Antelope Peak (see MP 295 above). The name was originally spelled Tachna, and was reportedly named after a 17th Century Greek patriarch named Tachnapolis, who moved here from California when he was quite elderly to live and work with the local Indians. Since he always had a light in his hut, the word “tachna” came to mean “bright spot” in the Papago Indian language. There are other interpretations of the origin of the name, but it is uncertain what the actual history was.
Visible to the south (right if eastbound) are the Copper Mountains, which are composed of Tertiary-aged granitic igneous and metamorphic rocks, flanked along their edges with younger Oligocene- to Miocene-aged sedimentary rocks. Antelope Hill (see MP 295 above) was likely originally part of the Copper Mountains, before much of the rock layers between here and the present mountain range were eroded away.
301.5 Pass through Colfred, a former Southern Pacific station named after Col. Fred Crocker, who was Treasurer of the railroad in 1881.
302.5 Cross usually-dry Mohawk Wash. Approximately one half mile south of the railroad, across the I-8 freeway, is the site of the Colfred Airport.
308 Cross Owl Wash and pass former community of Owl.
310-311 Pass through Mohawk and Mohawk Pass, in thee Mohawk Mountains. At the Pass, approximately MP 310.5, we cross a somewhat lower area. This is the location of a detachment fault, which is a type of thrust fault in which a block of older rocks is thrusted forward and overturned so much that it rests above rocks of much younger age. At this location, the block on the west side of the fault is composed of rocks of very old Proterozoic (Precambrian) age (2500 million years old), primarily metamorphosed volcanic rocks, as well as schist and gneiss. The block on the east side of the fault is composed of granitic and dioritic igneous intrusive rocks of Late Cretaceous (70 million years old) to Early Tertiary age.
311 Pass beneath Interstate 8. We are now crossing the San Cristobal Valley.
318 Pass through old railroad station of Stoval, a contraction of the name ”San Crystoval Valley (former name of San Cristobal Valley).
On the right (eastbound) is part of the Barry M. Goldwater Air Force Range, formerly known as Luke Air Force Range. This is a bombing range primarily used for air-to-ground bombing practice by United States Air Force pilots flying A-10s from Davis-Monthan AFB, F-16s from Luke AFB and Tucson ANGB, and U.S. Marine Corps pilots and naval flight officers in F/A-18s and AV-8B Harriers flying from MCAS Yuma. It is also used by other U.S. and NATO/Allied/Coalition flight crews while deployed to any of the aforementioned bases for training. The U.S. Air Force operates the eastern portion of the Range (south of Interstate 8), while the U.S. Marine Corps operates the western portion.
323.5 Pass through the unincorporated community of Dateland, named after its abundance of date palm trees. The Dateland Food Court is home to the self-proclaimed "World Famous Date Shakes."
327 Note small Dateland Airfield on the left (eastbound) across I-8. The Aztec Hills, visible on the right, are composed of Precambrian granitic and dioritic intrusive igneous rocks, of Proterozoic age.
329 Pass through Aztec.
335 On the left (eastbound) is an agricultural inspection station along Interstate 8. We are now entering the Sentinel Plain, a large area of Pliocene-aged to Recent basaltic lava flows, erupted in the very recent geologic past, within the last 2 million years. The primary volcanic peak was Sentinel Peak, which was a very small volcanic center, which did not have the large buildup of lava around its event such as the larger volcanic peaks in the Western United States have. The deposition of these lava flows likely diverted the flow of the Gila River, north of here.
336 Enter MARICOPA County, which was created on February 12,1871, from Yavapai County. It was the 6th county created in Arizona Territory, and is currently the most populous county in Arizona, and the 4th most populous county in the Nation. Its county seat is Phoenix. The county was named after the Maricopa Indians.
337 Pass through Stanwix, which was another station on the Butterfield Overland Mail stage line. It was formerly known as Flap-jack Ranch, and later as Grinnell’s Ranch. It had a facility for bathing. Stanwix was established in 1858, and some researchers claim it was the site of the westernmost battle of the American Civil War; however, others claim that the Battle of Picacho Pass (see MP 462.5 below) should claim that honor.
The Battle of Stanwix Station took place on March 29, 1862, when Union Captain William P. Calloway and a vanguard of 272 troops from the California Column discovered a small detachment of Confederates led by 2nd Lt. John W. Swilling burning hay, which had been placed at Stanwix Station for the California Column's animals. After a brief exchange of gun fire with the much larger Union force, the Confederates retreated to Tucson, the capital of the western district of the Confederate Territory of Arizona. The skirmish resulted in the wounding of a German-born Union private, William Frank Semmelrogge, who subsequently recovered. There appear to have been no other casualties. Two weeks later, the larger and more significant Battle of Picacho Pass took place (see MP 455 below).
338-340 Leave the Sentinel Plain basalt flows here for a couple miles.
340.5-341 On the left (eastbound), on I-8,are the eastbound and westbound Sentinel Rest Areas
343.5 Pass through Sentinel, named after nearby Sentinel Peak, which was so named for the fact that, when the railroad came through here, the peak “stood out like a sentinel in the desert.”
350-352 On the right (eastbound) is another part of the Barry M. Goldwater Air Force Range (see MP 318 above).
355 At approximately here, we are leaving the Sentinel Plain lava flows. North of the railroad (left if eastbound), the jagged hills visible in the distance are composed of Oligocene- to Miocene-aged volcanic rocks.
357.5 Pass through Piedra, another former railroad station on the Southern Pacific line. The Spanish word piedra means “stone” or “rock.” This station was established around 1890.
358-359 South of the railroad (right if eastbound) can be seen a small outlier of the Sentinel Plain lava flow, and south of the blocky lava, the small hill visible from the railroad is a small shield volcano, approximately 2 million years old. This feature is also an outlier of the Sentinel Plain lava field.
On the left (eastbound) is the large Solana Generating Station, a solar power plant completed in 2013. The plant was built by the Spanish company Abengoa Solar, and had a total capacity of 280 MW, enough to power 70,000 homes per year.
363 Pass through Theba, once an important melon producing area. The Rowley Mine, a private copper mine known as a source of the mineral wulfenite, a lead molybdate mineral (PbMoO4), is located near here. The large Paloma Ranch is also located here, and many residents are employed on the ranch. Because of this, the area is sometimes shown as Paloma on maps. The Paloma Ranch landing strip is visible on the right (eastbound).
366 Cross Gila Bend Canal, an agricultural canal.
372 Pass beneath Interstate 8.
372.5-374 Pass through Gila Bend, so named after the nearly 90º bend in the Gila River north of town. There was an ancient Hohokam Indian village near here, and in 1699, the area was visited by Fr. Eusebio Francisco Kino, who found several groups of Pima and Cocomaricopa (known as the “Opa”) Indians in the region.
Just west of town, in 1851, the Oatman Massacre, a conflict of the Yuma War, took place. During that conflict, 6 members of the Oatman family, an immigrant family traveling to California along the Gila River in Arizona, were murdered, supposedly by the Maricopa Indians. Two young girls, Olive and Mary Ann Oatman, were kidnapped, and later sold as slaves to the Mohawk Indians. Mary Ann died of starvation, but Olive was later ransomed. Later investigation and accounts indicated that the attacking group may have actually been either the Mohawk or Yavapai Indians, and not the Maricopa.
By 1857, Gila Bend was a stop on the Butterfield Overland Mail stage line, and soon the railroad also came through the area. For a while, Gila Bend was known as the ”Crossroads of the Southwest,” after the numerous stage, wagon, and rail lines converged here.
In the 1880’s, a saloon called “Whiskey, the Road to Ruin” was located here, as well as the currently existing welcome sign, which welcomes travelers to Gila Bend, a city of “1700 friendly people and 5 old crabs.” In 2006, the band Los Lobos recorded a song entitled “The Road to Gila Bend.” Gila Bend is also the home of the Gila Bend Museum, which displays historic artifacts from the area.
374 Cross Sand Tank Wash
374.5 Pass beneath Interstate 8
375.5 On the left (eastbound), the Gila Bend Municipal Airport is visible.
380.5 Pass through Bosque, which is a Spanish word for “forest” or “grove.” In 1895, when the railway station was established, the Phoenix Wood & Coal Company began cutting wood in the area for shipment to Phoenix. They were then arrested by U.S. Marshalls for cutting timber on government land, and 5000 cords of timber were seized by the government. Eventually the lumber was released, however, at a cost of 25 cents per acre to the government for cutting timber on public lands.
Visible on the south (right if eastbound) are the Sand Tank Mountains, which are composed of Precambrian-aged (Early Proterozoic) metamorphic rocks, which were intruded much later in geologic time by Tertiary-aged volcanic rocks and lava flows. There was also extensive block faulting in the area during Tertiary time.
385-387 Pass through the Maricopa Mountains, which are also composed of Early Proterozoic-aged metamorphic rocks capped by Oligocene- to Miocene-aged sedimentary rocks and some volcanic flow rocks.
On the left (eastbound) is part of the 486,000-acre Sonoran Desert National Monument, which was created by Presidential Proclamation of President Bill Clinton on January 17, 2001. As part of the Proclamation, the President mandated that all livestock grazing within the Monument south of Interstate 8 be ceased at the end of the current permit durations. The Monument is managed by the U.S. Bureau of Land Management.
The Monument contains an array of wildlife, including bighorn sheep, mule deer, bobcats, desert tortoises, owls, bats, and several endangered species. The ancestors of the modern Quecham, Maricopa, and O’odham Indians once roamed the area, and the Monument contains many historic archeological sites.
387-388 The westbound and eastbound tracks diverge here for approximately one mile. Pass through Shawmut.
389-391 Another block of the Maricopa Mountains is adjacent to the railroad one the left (eastbound).
392 Pass through Estrella, named after the nearby Estrella Mountains. The name is a Spanish word for “star.”
394 On the right (eastbound) is another small hill composed of Early Proterozoic- (Precambrian) aged granitic and dioritic rocks.
397 We are now crossing the Vekol Valley. The numerous small hills south and north off the railroad are composed of various types of Early Proterozoic-aged igneous, sedimentary, and metamorphic rocks. “Vekol” is a Papago Indian word meaning “grandmother.” The Valley was named after a nearby mine.
401.5 Pass through Mobile
406 Pass through Enid and enter PINAL County. Pinal County was established on February 1, 1875, and was created from parts of Maricopa and Pima Counties. Between 2000 and 2010, it was the second fastest growing county in the Nation. “Pinal” is an Apache Indian word for “deer.”
Several Native American communities make their homes in Pinal County, including the Tohono O’odham, Nation, the Gila River Nation, and the Ak-chin Indian community. The county seat is Florence.
Visible to the north (left if eastbound() are the Sierra Estrella Mountains, and the Palo Verde Mountains are visible to the south. These ranges are composed of Early to Middle Proterozoic-aged metamorphic and granitic igneous intrusive rocks.
410 Pass through Heaton. The Southern Pacific Railroad, at one time, proposed building a branch rail line from here to Phoenix, since it would have been shorter than the existing line (not used by AMTRAK) from Maricopa to Phoenix, but the line was never built. Heaton was formerly known as Maricopa or Maricopaville.
412 On the left (eastbound) is Southern Dunes Golf Club.
415 MARICOPA station, 19427 N. John Wayne Parkway. Elevation approximately 1176. This is the AMTRAK station which serves Phoenix, which is located approximately 30 miles north of here. The former Southern Pacific line (now Union Pacific) through Phoenix was abandoned by AMTRAK several years ago due to deteriorated track conditions, and the so-called “Gila Bend line” was then used by AMTRAK. Until 2005, a restored dome car from the old California Zephyr was used as the Maricopa station. The city of Maricopa is now considerably larger than what is shown on the accompanying topographic maps.
Maricopa was named after the Maricopa Indians, and is the 2nd most populous incorporated city in Pinal County, and the 18th most populous in the State. The city got its start as the community of Maricopa Wells, several miles north of here. Maricopa Wells had an abundant supply of water from deep wells for passengers and horses of the San Antonio-San Diego Mail and later the more famous Butterfield Overland Mail stage lines. In 1879, the city moved to the site of nearby Heaton (see MP 410 above), from where a rail line was once proposed to be built to Phoenix. In the 1880’s, the city moved to its present location, and the Maricopa & Phoenix Railroad was completed in 1887. The city of Maricopa, however, was not officially incorporated until October 15, 2003.Maricopa today is a largely residential area. It was once the home of Actor John Wayne