Effects of Weathering, Erosion and Deposition Texas Ecoregions Effects of Weathering, Erosion and Deposition

Factors Affecting Our Ecoregions Weathering – chemical and physical break down of rocks into sediment Erosion – the movement of sediment from one place to another Deposition – the placement of sediment after being carried from place of origin

1. Piney Woods This ecoregion is found in Southeast Texas. It is the wettest region of the state with an average annual rainfall of 36-50 inches. This allows for a high rate of decomposition to occur resulting in healthy, nutrient-rich soils. The topography is gently rolling to near flat through out the region. Pine trees, woody vines, and hardwood trees dominate the vegetation. It is a fire climax system. Fire is necessary in order for pines to maintain dominance in the area. Unless an area has been clear-cut of vegetation for construction, the amount of trees and plants can prevent erosion.

3. Blackland Prairies This ecoregion is located along the northern-centeral portion of Texas These areas have nutrient-rich soils and receive good amounts of rainfall through the year with an average rainfall of 28-40 inches. If the land is clear-cut of natural vegetation for construction nutrients can easily be eroded. If the land is used for farming and it is not managed well, nutrients will be quickly used up.

4. Gulf Coastal Prairie & Marshes This ecoregion is found along the Gulf coast. Soil in the region is primarily sand-based. If there isn’t enough vegetation to keep the soil in place, rainfall received can cause severe erosion with 30-50 inches per year. Catastrophic events such as hurricanes can increase wave erosion and deposition.

6. South Texas Brush Country This area is found in south-western Texas The area is known as “Brush Country” due to the shorter trees and many shrubs. Average rainfall rates are between 20-32 inches Overgrazing of the land has allowed nutrient-rich topsoil to erode way. Rocky, dry soil cannot support grasses, trees can thrive because of their deeper root system.

7. Edwards Plateau This region is located between dry western plains and moist prairies and woods in Western Texas Unfortunately, erosion has left most of the region with very shallow soils (less than 10 inches) lined with limestone rock layers. High amounts of rain in a short amount of time can cause flash flooding. Average annual rainfall is between 15 and 34 inches.

9. Rolling Plains This region is part of the Great Plains of the central United States and is located in north centeral Texas. Soils in this area are most fertile and sought after for crop production. Periods of drought and then sudden increase in rainfall causes large amounts of erosion and deplete the soil of nutrients. The average rainfall is between 20 and 28 inches

10. High Plains This ecoregion is located in the northern most part of Texas known as the “Texas Panhandle” This ecoregion is the largest and most completely flat areas of it size in the world! The region extends to the Palo Duro Canyon-the nations 2nd largest canyon. Palo Duro Canyon was formed by water erosion from the Prairie Dog Town Fork of the Red River. 15-22 inches of rainfall each year deepens the canyon by moving sediment downstream. Wind and water erosion gradually widen the canyon.

11. Trans-Pecos This ecoregion is located in the western-most area of Texas Rain does not fall evenly over the area. “Desert portion” of Texas with less than 12 inches per year The weathered bedrock in this area has high amounts of calcium As a result of erosion and deposition in the area, the soil has high amounts of calcium called caliche.