Giant Redwood(California) and the Grand Canyon(Arizona) Giant Redwood and Bristlecone PineTrees. General Sherman, a giant redwoood tree in the Sequoia Nation Park measuring 84 metres tall, is the largest plant in the world. It is also 3.000 years old, but it isn't the oldest tree in the world! That's also in California. The bristlecone pine grows in the White Mountains, and it is the oldest living thing on earth. The most famous, named Methuselah, is over 4,000 years old. Grand Canyon. The Grand Canyon, eroded over thousand of years by the Colorado River and its tributaries, is 400 km long . It is 2,000 metres deep at its deepest point and 30 km wide at its widest point. It is one of the most important geological sites in the world ( some of the rocks are over 1,800 million years old) and it is home to a great diversity of wildlife.