Final answer:
The canyons such as the Black Canyon of the Gunnison and the Grand Canyon were formed by the erosion of rivers cutting through bedrock. The bedrock, composed of ancient metamorphic rocks like gneiss and schist, and igneous rocks, predates the canyons, indicating the rocks were there before the canyons formed.
Step-by-step explanation:
The question 'Did the canyon exist before the black rock formed?' seems to refer to geological processes that shape landforms such as canyons. To answer it, regarding the formation of canyons like those in the Black Canyon of the Gunnison National Park or the Grand Canyon, it is crucial to understand that the canyons were formed by erosional processes, primarily from the persistent action of rivers. The Black Canyon was gradually carved by the Gunnison River, which cut through the ancient metamorphic rocks like gneiss and schist, and the Grand Canyon was formed by the erosional forces of the Colorado River over millions of years.
Metamorphic rocks such as gneiss and schist, present in the walls of the Black Canyon, are very old, nearly 2 billion years old, and they indicate the presence of ancient geological events like the intrusion of igneous rocks and the extreme pressures and temperatures below the earth's surface. The canyons themselves, however, are relatively younger features formed by the erosional action of rivers. In the case of the Grand Canyon, it is debated whether its formation began with the Colorado River's erosion only 5 million years ago or during the Laramide Orogeny 50 to 70 million years ago. Analyzing the rocks' ages and faults that the Colorado River cuts through can support these hypotheses.
In conclusion, the canyons were likely formed after the appearance of the black rocks, which are igneous and metamorphic, thus suggesting the rock existed prior to canyon formation.