The Seven Wonders of the World Since ancient times, numerous “seven wonders” lists have been created. The content of these lists tends to vary, and none is definitive. The seven wonders that are most widely agreed upon as being in the original list are theSeven Wonders of the Ancient World,which was compiled by ancient Greek historians and is thus confined to the most magnificent structures known to the ancient Greek world. Of all the Ancient Wonders, the pyramids alone survive. The Pyramids of Egyptare three pyramids at Giza, outside modern Cairo. The largest pyramid, built by Khufu (Cheops), a king of the fourth dynasty, had an original estimated height of 482 ft (now approximately 450 ft). The base has sides 755 ft long. It contains 2,300,000 blocks; the average weight of each is 2.5 tons. Estimated date of completion is 2680B.C. TheHangingGardensof Babylonwere supposedly built by Nebuchadnezzararound 600B.C.to please his queen, Amuhia. They are also associated with the mythical Assyrian queen Semiramis. Archeologists surmise that the gardens were laid out atop a vaulted building, with provisions for raising water. The terraces were said to rise from 75 to 300 ft. TheStatue of Zeus (Jupiter) at Olympiawas made of gold and ivory by the Greek sculptor Phidias(5th centuryB.C.). Reputed to be 40 ft high, the statue has been lost without a trace, except for reproductions on coins. TheTemple of Artemis(Diana) at Ephesuswas begun about 350B.C., in honor of a non-Hellenic goddess who later became identified with the Greek goddess of the same name. The temple, with Ionic columns 60 ft high, was destroyed by invading Goths inA.D.262. TheMausoleum at Halicarnassuswas erected by Queen Artemisia in memory of her husband, King Mausolusof Caria in Asia Minor, who died in 353B.C.Some remains of the structure are in the British Museum. This shrine is the source of the modern wordmausoleum. The Colossus at Rhodeswas a bronze statue of Helios (Apollo), about 105 ft high. The work of the sculptor Chares, who reputedly labored for 12 years before completing it in 280B.C., it was destroyed during an earthquake in 224B.C. The Pharos(Lighthouse) of Alexandriawas built by Sostratus of Cnidus during the 3rd centuryB.C.on the island of Pharos off the coast of Egypt. It was destroyed by an earthquake in the 13th century. (Some lists include the Walls of Babylonin place of the second or seventh wonder.)

Michigan and Huron: One Lake or Two? It is a widely accepted fact that Lake Superior, with an area of 31,820 square miles, is the world's largest freshwater lake. However, this fact is based on a historical inaccuracy in the naming of Lake Huron and Lake Michigan. What should have been considered one body of water, Lake Michigan-Huron with an area of 45,410 square miles, was mistakenly given two names, one for each lobe. The explorers in colonial times incorrectly believed each lobe to be a separate lake because of their great size. Why should the two lakes be considered one? The Huron Lobe and the Michigan Lobe are at the same elevation and are connected by the 120-foot-deep Mackinac Strait, also at the same elevation. Lakes are separated from each other by streams and rivers. The Strait of Mackinac is not a river. It is 3.6 to 5 miles wide, wider than most lakes are long. In essence, it is just a narrowing, not a separation of the two lobes of Lake Michigan-Huron. The flow between the two lakes can reverse. Because of the large connecting channel, the two can equalize rapidly whenever a water level imbalance occurs. Gauge records for the lakes clearly show them to have identical water level regimes and mean long-term behavior; that is, they are hydrologically considered to be one lake. Historical names are not easily changed. The separate names for the lake are a part of history and are also legally institutionalized since Lake Michigan is treated as American and Lake Huron is bisected by the international boundary between the United States and Canada. Of all the world's freshwater lakes, North America's Great Lakes are unique. Their five basins combine to form a single watershed with one common outlet to the ocean. The total volume of the lakes is about 5,475 cubic miles, more than 6,000 trillion gallons. The Great Lakes are Superior, with an area of 31,820 square miles (82,414 km) shared by the United States and Canada; Huron, with an area of 23,010 square miles (59,596 sq. km) shared by the United States and Canada; Michigan, with an area of 22,400 square miles (58,016 sq. km) entirely in the United States; Erie, with an area of 9,930 square miles (25,719 km) shared by the United States and Canada; and Ontario, with an area of 7,520 square miles (19,477 km) shared by the United States and Canada.

The Continental Divide The Continental Divide is a ridge of high ground that runs irregularly north and south through the Rocky Mountains and separates eastward-flowing from westward-flowing streams. The waters that flow eastward empty into the Atlantic Ocean, chiefly by way of the Gulf of Mexico; those that flow westward empty into the Pacific. Every continent with the exception of Antarctica has a continental divide.

Mason and Dixon's Line Mason and Dixon's Line (often called the Mason-Dixon Line) is the boundary between Pennsylvania and Maryland, running at a north latitude of 39°43'19.11". The greater part of it was surveyed from 1763–1767 by Charles Mason and Jeremiah Dixon, English astronomers who had been appointed to settle a dispute between the colonies. As the line was partly the boundary between the free and the slave states, it has come to signify the division between the North and the South.

World Heritage Sites in the United States The United Nations Educational, Scientific, and Cultural Organization (UNESCO) has identified 878 World Heritage sites that it considers of “outstanding universal value.” In the United States, there are 20 of these sites; the 17 that are natural sites are listed below. The World Heritage Web site is as follows: http://whc.unesco.org /en/list/. Cahokia Mounds State Historic Site, Illinois:BetweenA.D.900 andA.D.1500 the Cahokia site was the regional center for the Mississippian Indian culture. Named for the Cahokia Indians who came after them, Cahokia features the largest prehistoric earthen constructions in the Americas, a testament to the sophisticated engineering skills of Mississippian culture. Carlsbad Caverns National Park, New Mexico:Carlsbad Caverns National Park is a network of more than 80 limestone caves, including the nation's deepest—1,597 feet—and third longest. The Lechuguilla Cave is particularly noteworthy for its beautiful stalagtites and stalagmites. Chaco Culture National Historical Park, New Mexico:BetweenA.D.900 andA.D.1100, the Anasazi built large multistory stone villages and an impressive 400-mile road system in Chaco canyon exemplifying their engineering and construction talents. Everglades National Park, Florida:The Everglades, or “River of Grass” as the Seminoles called it, is formed by a river of fresh water 6 inches deep and 50 miles wide that flows slowly across the expanse of land of sawgrass marshes, pine forests, and mangrove islands. More than 300 species of birds live in the park as well as alligators, manatees, and Florida panthers. Glacier Bay National Park and Preserve, Alaska:The park is made up of a huge chain of great tidewater glaciers and a dramatic range of landscapes, from rocky terrain recently covered by ice to lush temperate rain forest. Brown and black bears, mountain goats, whales (including humpbacks), seals, and eagles can be found within the park. Grand Canyon National Park, Arizona:The Grand Canyon is among Earth's greatest ongoing geological spectacles. About 65 million years ago in Earth's shifting, a huge area of land was lifted a mile and a half above sea level, forming what is now the Colorado Plateau. For the last 6 to 10 million years, the Colorado River has been slowly carving its way down through the center, exposing the many colorful strata of rock. Great Smoky Mountains National Park, North Carolina/Tennessee:“Place of Blue Smoke” was the name given by the Cherokee Indians to these Appalachian Highlands. The forest here exudes water vapor and oily residues which create a smoke-like haze that surrounds the peaks and fills the valleys. The park is one of the world's finest temperate deciduous forests. Hawaii Volcanoes National Park, Hawaii:It is thought that the Hawaiian islands were created when molten rock pushed through Earth's crust, forming volcanoes. The two most spectacular live volcanoes are Kilauea and Mauna Loa. Mammoth Cave National Park, Kentucky:Mammoth Cave, as its name suggests, is the world's most extensive cave system, with 345 miles of passages. Water seeping into the cave creates stalactites, stalagmites, and white gypsum crystal formations. Rare and unusual animals, such as blind fish and colorless spiders, demonstrate adaptation to the absolute blackness and isolation. Mesa Verde National Park, Colorado:In the sixth century, the Anasazi, or “Ancient Ones,” established villages on the high, flat land in southwestern Colorado. In the late 1100s they began constructing multistory stone apartment houses, or pueblos, tucked on ledges and under rock overhangs. Olympic National Park, Washington:The park encompasses not only snow-capped Mount Olympus, glaciers, alpine meadows, and rocky Pacific Mountain coastline, but also one of the few temperate rain forests in the world. The luxuriant forest is created by the warm, moisture-laden air from the Pacific meeting the mountains, resulting in a dense, green, jungle-like world. Papahanaumokuakea:This string of isolated islands is the largest conservation area in the United States and one of the largest marine conservation areas in the world. It covers 139,797 square miles of the Pacific Ocean. The extensive coral reefs found in Papahanaumokuakea are home to more than 7,000 marine species, one-quarter of which are found only in the Hawaiian Archipelago. Many of the islands and shallow water environments are important habitats for rare species, such as the threatened green sea turtle and the endangered Hawaiian monk seal. Papahanaumokuakea is also of great cultural importance to Native Hawaiians with significant cultural sites found on the islands of Nihoa and Mokumanamana.Source: http://papahanaumok uakea.gov.