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.

Question: "When does Las Vegas history begin and what covered most of the area?"

Response: "Caves"

A: no

We need natural resources for just about everything we do. We need them for food and clothing, for building materials and energy. We even need them to have fun. Table 2.1 gives examples of how we use natural resources. Can you think of other ways we use natural resources? Use Vehicles Resources Rubber for tires from rubber trees Steel frames and other metal parts from minerals such as iron Example iron ore Electronics Plastic cases from petroleum prod- ucts Glass screens from minerals such as lead lead ore Use Homes Resources Nails from minerals such as iron Timber from trees Example spruce timber Jewelry Gemstones such as diamonds Minerals such as silver silver ore Food Sunlight, water, and soil Minerals such as phosphorus corn seeds in soil Clothing Wool from sheep Cotton from cotton plants cotton plants Recreation Water for boating and swimming Forests for hiking and camping pine forest Some natural resources are renewable. Others are not. It depends, in part, on how we use them.

Question: "What are natural resources needed for?"

Response: "Shelter"

A: yes

Tropical climates are found around the equator. These climates have warm temperatures year round. Tropical climates may be very wet or wet and dry. Tropical wet climates occur at or very near the equator. They have high rainfall year round. Tropical rainforests grow in this type of climate. Tropical wet and dry climates also occur near the equator. They receive less rainfall. Most of the rain falls in a single season. The rest of the year is dry. Few trees can withstand the long dry season. The main plants are grasses. Dry climates receive very little rainfall. They also have high rates of evaporation. This makes them even drier. Deserts can get less than 25 centimeters of rain per year. Thats less than 10 inches per year. How much rain do you get at your house?

Question: "How much rainfall do the deserts receive?"

Response: "Less than 10 inches per year"

A:
yes