Download Chapter 1 Geography of Texas Notes

Chapter 1 Geography of Texas Notes:
I.
Sizing up Texas:
A. Texas is the 2nd largest state in the U.S. Only Alaska is bigger.
B. The total area of Texas is 268,581 square miles.
C. This is 7% of the total area of the United States.
II.
Viewing Landforms of Texas:
A. The southernmost point in Texas lies on a mostly level plain. This point is very near
sea level where Texas meets the Gulf of Mexico.
B. Running along the southern coast a few miles offshore is Padre Island. This long thin
strip of land covered with sand dunes is a barrier island protecting the mainland shore
from ocean waves. The bay between Padre Island and the mainland is a rich fishing area.
C. Moving northward, the land slowly rises and begins to gently roll. This part of Texas
is covered with a tough and prickly mixture of grasses, mesquite trees, cacti, blackbrush,
and other plants that thrive in a hot, dry climate.
D. Cutting across Texas in a great curving arc is an escarpment, or long cliff. The
Balcones Escarpment, formed millions of years ago by a giant earthquake, follows a weak
part in the earth’s crust called a fault. Long ago, the land sank east and south of the fault.
North and west of it, the land rose many feet, forming the escarpment.
E. The Balcones Escarpment marks the beginning of a region of Texas known as the “hill
country.” This part of Texas is a plateau, or tableland, covered with small trees and brush.
F. Hills on the rim of the plateau were formed by streams cutting and smoothing over the
plateau’s limestone edges. There are more streams and rivers in this part of Texas than in
any other.
G. The land gradually gets flatter and higher as you travel northwest. One abrupt change
disrupts this plains region. The Caprock Escarpment, also formed along a fault, has cut
great gashes in the caprock. Palo Duro and Tule Canyons hold some of the most beautiful
scenery in Texas.
H. A trip starting at the easternmost point in the state would also begin on a plain.
Again, the level of the land gently rises as you travel westward, after crossing the
Balcones Escarpment and the hill country; you finally reach the plains to the west.
I. West Texas has landforms that do not appear in other parts of the state. Most
noticeable are the mountains, which are a part of the Rocky Mountain Range. This part of
Texas has 91 mountains more than one mile high.
III. Water Resources:
A. “Wrong Way” Rivers of Texas: Texas Rivers are sometimes called “wrong way”
rivers because they carry water from the dry part of the state, where it is needed, to the
eastern part, which normally has plenty of water.
B. To keep precious water from running unchecked into the Gulf of Mexico, many rivers
in Texas have been dammed, forming lakes.
C. The Rio Grande: The Rio Grande, which forms the southern border of Texas, is one
of the longest rivers in the United States – almost 2,000 miles in length. The Rio
Grande was formed between 15 and 30 million years ago, when forces within the
earth caused the crust to drop forming a rift, or gash, more than 5 miles deep in places.
The basins of the rift filled with runoff rain and snow to form inland seas. Earthquakes
caused the seas to overflow, and the Rio Grande was formed. The river connected
basin after basin, finally reaching the sea about a half-million years ago.
D. Texas Lakes: Texas has nearly 200 lakes. Texas ranks third behind Alaska and
Minnesota in the surface area of its inland waters. All but one of the lakes were
formed when rivers were dammed. Only Caddo Lake in East Texas began as a natural
lake. Now, even Caddo Lake has been dammed.
a. Uses for Texas Lakes: Flood control, Water conservation, Irrigation, Water for
cities and towns, and Manufacturing
E. Aquifers: Aquifers are another major water source in Texas. Aquifers are natural
underground water reservoirs, which are replenished with rainfall. Enormous amounts
of water are pumped from the aquifers to supply the water needs of cities and irrigate
farms.
a. The Edwards Aquifer: The Edwards Aquifer is found between the cities of
Austin to San Antonio. Large amounts of rainfall refill this aquifer, making it a
dependable source of water for years to come.
b. The Ogallala Aquifer: The future of this aquifer remains a major concern. It
lies beneath the Texas High Plains, a region of Texas that does not have a
dependable supply of rainfall. More than 5 million acres are irrigated by this
aquifer, and its levels continue to decline.
F. Pollution: Not every Texan is concerned with protecting our water resources. Wastes
and chemicals from cities, factories, and fields often empty into our rivers, lakes,
aquifers, and bays. Because of this pollution, fish and seafood is sometimes declared
unsafe to
eat.
IV.
Three Vegetation Regions:
In general, Texas has three types of natural vegetative regions: forests (for timber),
grasslands (for farming), and savannas (for ranching)
A. Forests: Three major forest regions are found in Texas, all in the eastern third of
the state where rainfall is greatest. Timber is one of the top cash crops in Texas,
usually outranked only by cotton. The lumber, plywood, and paper industries
provide many jobs in East Texas.
B. Grasslands: Early settlers established farms on the grasslands because they had to
clear only a few trees. These areas are still major farming areas.
i. Soil is a valuable resource: The rich soil of Texas is one of its most
valuable resources. Major crops include cotton, spinach, watermelons,
wheat, rice, corn, soybeans, vegetables, and peanuts.
C. Savannas: Much of central and west Texas has a dry, rocky soil that supports only
short grasses and small desert shrubs, and in some places scattered trees.
D. Land that is not suitable for farming can often be used for ranching. Texas usually
leads the nation in the number of cattle, sheep, and goats raised, and in the amount
of wool and mohair clipped.
V.
Natural Mineral Resources:
A. Texas is the nation’s most important producer of minerals.
B. It leads the nation in the production of mineral fuels, with petroleum the most
valuable and natural gas the second most valuable.
C. One-fourth of all the energy produced in the entire history of the United States has
been produced in Texas.
D. Texas produces about 1/5 of the nation’s salt. You can find salt mines and domes
in many parts of the state.
E. Coal is found in north central and west Texas. A low-grade coal, called lignite is
found along the coastal plain. Coal is used to fuel boilers, steam-engines, and
furnaces.
F. Sulfur is used in insecticides and gunpowder.
G. Gypsum is used to produce drywall for construction.
H. Granite and limestone are used for building.
I. Clay, lead, iron, magnesium, zinc, and uranium are also mined in Texas.
VI.
The Climate of Texas:
A. Hot summers and mild winters generally characterize Texas’s climate; however,
Texas covers such a large area that other factors contribute to its climate as well.
B. These factors include: Absolute location, Relative location, and Elevation
C. Absolute Location: Texas lies in what are called the “middle latitudes,” the region
about midway between the equator and the North Pole. Because Texas is not very
far from the Equator, it experiences warmer weather. South Texas is milder than
North Texas.
i. The middle latitudes are also a meeting place of cool air moving from the
north and moist, warm air moving from the Gulf of Mexico. Violent storms
may result from this mixing of cold and warm air. These may produce
thunderstorms, hail, and tornadoes. Texas has an average of 153 tornadoes
each year.
D. Relative Location: The location of Texas relative to the Gulf of Mexico has a
major influence on the climate of the state. Most of the year, winds blow inland
from the coast for 200 miles or more. These gulf breezes cool Eastern Texas in the
summer and warm it in the winter. Moisture from the gulf is the source of most of
the rain that falls on our state. Hurricanes and tropical storms also originate in the
gulf.
E. Elevation: In general, the average temperature cools about 3 degrees for each
1,000-foot rise in elevation. Mountainous areas receive more rainfall because
cooler air is less able to hold moisture. On the northern plains, there are no
mountains to block powerful northers.