That would be 75% of Earth's atmosphere.
Answer:
Rivers of the Coastal Plain were a major means of commercial transportation during the 1700s and early 1800s. Cities founded along the fall line, called “fall line cities,” are located at the places where these rivers crossed the fall line, marking the upstream limit of travel. The city of Columbus, for example, was established where the Chattahoochee River crosses the fall line; Macon, Milledgeville, and Augusta are similarly located at the crossings of the Ocmulgee, Oconee, and Savannah rivers, respectively. These cities became important transportation hubs because traders could only travel upstream until they reached the waterfalls of the fall line. At that point they were forced to disembark and reload their cargo on the other side of the falls in order to continue their journeys. Columbus served as the upstream head of navigation for the Chattahoochee, as did Augusta for the Savannah River and Macon for the Ocmulgee River. After the first steamship arrived in 1828, Columbus became a gateway city for cotton. Above the fall line, flatboats and barges moved goods around the state. Below the fall line, steamships had unimpeded access to move goods, mostly cotton, into the Gulf of Mexico.
optical telescope (Hubble), X ray telescope ( Chandra) etc.
get around the Earth's atmosphere so that we can get a clearer view of the planets, stars, and galaxies that we are studying.
B. plate tectonics your welcome
