Final answer:
Roosevelt and environmental groups were justified in their support for the creation of Grand Canyon National Park, as it was a significant measure in protecting natural wonders and resources from the rampant industrial exploitation happening at the time. Through his actions, Roosevelt helped affirm conservationism and the value of preserving wilderness for future generations.
Step-by-step explanation:
President Theodore Roosevelt and environmental groups' support for the creation of Grand Canyon National Park was largely justified in light of the exploitation of natural resources that had escalated prior to his presidency. As industries were rapidly depleting the forests, prairies, and wildlife due to the belief that America's natural resources were inexhaustible, Roosevelt took significant steps to protect the country's environment. He was influenced not only by his personal enjoyment of the outdoors and sportsmanship but also by key figures such as John Muir, the founder of the Sierra Club, who promoted the intrinsic value of wilderness.
Roosevelt's actions set the groundwork for the modern conservation movement by establishing national parks, wildlife sanctuaries, and forest reserves. His creation of Grand Canyon National Park helped in preserving its majesty and natural beauty for future generations, and also reflected the changing American values towards conservationism and preservationism. With the establishment of the National Park Service in 1916, a more structured framework for maintaining and protecting the national parks was created, adhering to the principles Roosevelt and others fought for.