Southwestern Texas, along the Big Bend of the Rio Grande, one of the last scenic frontiers of America is located in a remote and unspoiled setting. Vast stretches of plains and range land, interspersed with numerous outcroppings of buttresses and ridges, end abruptly against a mass of mountains near the Mexican border. Etched and carved by the master hand of “Erosion” giant arroyos and imposing gorges are spread through the area in wild abandon. Towering, jagged peaks of the Chisos Mountains merge with the desert, plains and valleys in Big Bend National Park to create a kaleidoscopic pattern of dramatic contrasts and striking grandeur. The northern approach to Big Bend is through Marathon. Leaving U. S. Highway 90 from this point, the Park boundary at Persimmon Gap is about forty miles over State Road 51. The Big Bend area is about 330 miles west of San Antonio and 220 miles southeast of El Paso. Alpine, the western gateway to Big Bend is 118 miles from the Basin of the Chisos Mountains, in the center of the Park. Embraced in the gigantic curve of the Rio Grande, the Park lies just across the river from Old Mexico, where many geological features have a profound influence on the scenic aspects of this area. On the east, majestically rising above the Boquillas Canyon, the Sierra del Carmen Range provides a picturesque backdrop for the mesquite and cactus covered plains. Two other canyons complete the international features on the south and west. At the southernmost boundary of the Park, and almost inaccessible, is the rugged Mariscal Canyon, where the Rio Grande has carved its tortuous channel through more than seven miles of limestone rock. Precipitous walls of this abyss are almost sixteen hundred and fifty feet in height. The most imposing and the most easily accessible of the three canyons is the Santa Elena, along the western boundary of Big Bend. [Illustration: SANTA ELENA CANYON—The majestic grandeur of the Big Bend area is emphasized by the towering walls of the Santa Elena Canyon. Here, where the Rio Grande emerges from the winding gorge, Mexico appears at the left, the United States on the right.] Here, a deep gash in the mesa de Anguila and Sierra Ponce marks the course of the river for eighteen miles. Through millions of years, the silt and gravel laden waters have continued their endless task of grinding away the limestone bit by bit until now the walls of the canyon rise perpendicularly more than fifteen hundred feet above the waters of the river. [Illustration: BOQUILLAS, MEXICO AND SIERRA DEL CARMEN RANGE—The Village of Boquillas is located in a picturesque setting along the Rio Grande and at the base of the Sierra del Carmen Range.] [Illustration: SIERRA DEL CARMEN RANGE—One of the outstanding scenic features of the eastern section of Big Bend National Park is Mexico’s picturesque Sierra del Carmen Range, which exceeds 8,000 feet in elevation.]