Flowing water causes sediment to move. Flowing water can erode both rocks and soil. You have already learned that materials can dissolve in water. With enough time, even rocks can be dissolved by water. This process happens really slowly. It may take over a million years to dissolve a rock. It doesnt matter how big the rock is. With enough time, flowing water can dissolve it. Moving water also has the ability to move small pieces of rock and soil. How can water move a rock? Doesnt it need energy? Of course, water gets its energy because it is moving. Moving water has kinetic energy. Things that have more energy can do more work. When water stops moving it will have no energy. It will no longer be able to move the rock and soil. When this happens the rock and soil will settle to the bottom of the calm water. Scientists call this process deposition.

Would deposition of or the moving of a particular rock take more energy?

Alexander earned the epithet "The Great" due to his unparalleled success as a military commander. He never lost a battle, despite typically being outnumbered. This was due to use of terrain, phalanx and cavalry tactics, bold strategy, and the fierce loyalty of his troops. The Macedonian phalanx, armed with the sarissa, a spear 6 metres (20 ft) long, had been developed and perfected by Philip II through rigorous training, and Alexander used its speed and maneuverability to great effect against larger but more disparate Persian forces. Alexander also recognized the potential for disunity among his diverse army, which employed various languages and weapons. He overcame this by being personally involved in battle, in the manner of a Macedonian king. In his first battle in Asia, at Granicus, Alexander used only a small part of his forces, perhaps 13,000 infantry with 5,000 cavalry, against a much larger Persian force of 40,000. Alexander placed the phalanx at the center and cavalry and archers on the wings, so that his line matched the length of the Persian cavalry line, about 3 km (1.86 mi). By contrast, the Persian infantry was stationed behind its cavalry. This ensured that Alexander would not be outflanked, while his phalanx, armed with long pikes, had a considerable advantage over the Persian's scimitars and javelins. Macedonian losses were negligible compared to those of the Persians. At Issus in 333 BC, his first confrontation with Darius, he used the same deployment, and again the central phalanx pushed through. Alexander personally led the charge in the center, routing the opposing army. At the decisive encounter with Darius at Gaugamela, Darius equipped his chariots with scythes on the wheels to break up the phalanx and equipped his cavalry with pikes. Alexander arranged a double phalanx, with the center advancing at an angle, parting when the chariots bore down and then reforming. The advance was successful and broke Darius' center, causing the latter to flee once again. When faced with opponents who used unfamiliar fighting techniques, such as in Central Asia and India, Alexander adapted his forces to his opponents' style. Thus, in Bactria and Sogdiana, Alexander successfully used his javelin throwers and archers to prevent outflanking movements, while massing his cavalry at the center.

How did Alexander change the use of the phalanx at the battle of Gaugamela?

The inhabited history of the Las Vegas Valley stretches to 23,000 b.c. , when much of the area was covered by a prehistoric lake. During this period, the indigenous people lived in caves, hunting the mammals that gathered at the shoreline. The landscape of the valley changed dramatically over the next 200 centuries. The glaciers feeding the lake melted away and the lake evaporated. Fossils tell an obscure story of man's slow and sporadic development. Around 3000 b.c. , native Archaic Indians began to develop a lasting hunting and gathering culture. By this time, the valley was in much the same geographic state as it exists in today, with one exceptionthe presence of artesian springs that bubbled to the surface in several areas. These springs fed a network of streams draining through the Las Vegas Wash to the Colorado River. The areas surrounding the springs were desert oases: sprawling collections of grasses, trees, and wildlife. Many springs lay in areas that would eventually become the center of the modern Las Vegas metropolis. For about 4000 years, the Archaics thrived in a culture that included many signs of early civilization. Signs of even more advancement appeared halfway through the first millennium a.d. , when the Anasazi Indians inhabited the valley. Far more progressive than the Archaics, the Anasazi utilized such formal agricultural techniques as irrigation to assist their harvest. This permitted the Anasazi to achieve a benchmark of advanced societythe ability to live in permanent shelters year-round without need to follow wildlife. Mysteriously, the Anasazi vanished from the valley around a.d.
Where were animals commonly found for food in Las Vegas dating back to 23,000bc?