These splendid caverns, halfway up the Italian “boot,” are among the country’s most beautiful. Even the approach to the Frasassi Caves is picturesque. The road winding inland from Italy’s Adriatic coast just north of Ancona follows the valley of the Esino River through a verdant landscape of gently rolling hills But as it approaches the foothills of the Apennines, the scene changes quite dramatically. Suddenly the road is hemmed in by the towering walls of the Gola di Frasassi—the Frasassi Gorge. Flowing into the Esino is another river, the Sentito, which has carved an even narrower canyon.
A change in the underlying rocks accounts for this abrupt change in scenery. Downstream the Esino flows among hills formed of soft shales. In the gorges it has carved its route downward through massive limestone formations. And it is in these limestone formations that the Frasassi Caves are found.
The region is an example of what geologists call a karst landscape—a limestone terrain that has been modeled by the dissolving action of slightly acidic groundwater. Karst regions usually include caves, such as those at Mammoth Cave in Kentucky, as well as sinkholes, disappearing rivers, and underground streams.
Also typical of karst regions is the development of cave formations, and the Frasassi Caves are no exception. Throughout the contorted network of passageways and chambers, the interconnected system of caverns is beautifully adorned with stalactites and stalagmites of all imaginable shapes and sizes. In some places large curtainlike formations are so thin that artificial lights shine through them as they would through frosted glass. Other formations resemble alabaster, beautifully colored in rainbow hues. Built up over the course of centuries, these features, known as speleothems, were formed as the minerals dissolved in slowly dripping water were redeposited within the caves.
Perhaps the most startling portion of the Frasassi Caves is the Grotta delle Nottole, the “Cave of the Bats”; it is named for the many colonies of bats that inhabit it. But the most Columbia, suggests the wildness of the canyon that is to come. The chasm itself follows the line of an ancient fault (a major fracture in the bedrock) that dates back some 50 million years. As the surface of the land rose slowly in the coastal ranges, the river carved its channel ever deeper along this zone of weakness until it had carved the awesomely rugged canyon that remains today.
Along most of its length the canyon is hemmed in by steep, lofty cliffs. In some places mountains as much as 3,000 feet (900 meters) high rise up virtually from the water’s edge. And the river hurtles along, in one observer’s words, “frantically tearing its way in foaming whirls.” At Hells Gate, where a landslide narrowed the river to a width of only 120 feet (37 meters), the water rushes by at a rate of 25 feet (8 meters) per second.
The surrounding landscape changes dramatically from one end of the canyon to the other. The northern end lies in a semiarid region where sagebrush flourishes in the hot, dry summer climate. Farther south, in contrast, rainfall is heavy, and the canyon is bordered by seemingly endless forests.
The full course of the river was first traced in 1808 by a party headed by the explorer and fur trader Simon Fraser, whose name the river still bears. Struggling through the treacherous canyon, the explorers found the Hells Gate section, in particular, to be especially challenging. “We had to pass,” wrote Fraser, “where no human being should venture.”
For the next half-century the river was used only by fur trappers and Indians. Then in 1857 gold was discovered along its banks just south of Yale, and a furious rush was on. Yale’s population climbed to 20,000, and a narrow track called the Cariboo Road was blasted out of the canyon walls. At one spot the road builders flung a suspension bridge across the deep gorge—the first such span in western North America.
By the late 1860′s, after $100 million in gold had been taken out of the area, the bonanza ran thin, and homesteaders began to replace miners on the Cariboo Road. Today two railroads as well as the Trans-Canada Highway wind through the tortuous canyon, running on beds that have been carved into the canyon walls above the river. Otherwise the Fraser River Canyon remains as wild and untamed as ever. Sarah writes for the Czech Travel Guide.