Category: Science - Earth/Agricultural/Farming
Page Preface vii Introduction 1 Earth’s outer crust 2 Geologists 2 Time and rock units 2 Geologic map 6 What are rocks and minerals? 7 Chemical elements 7 Minerals 7 Rocks 8 Igneous rocks 9 Extrusive or volcanic igneous rocks 9 Intrusive igneous rocks 9 Sedimentary rocks 10 So...
Page Preface vii Introduction 1 Earth’s outer crust 2 Geologists 2 Time and rock units 2 Geologic map 6 What are rocks and minerals? 7 Chemical elements 7 Minerals 7 Rocks 8 Ign...
2. Part 2Some of the rock fragments carried by water are still fairly large when they reach their destinations. On the basis of size, they are called _boulders_, _cobbles_, _pebbles_, an...
3. Part 3To help you identify them, various Texas rocks and minerals are listed together in the following charts according to properties that they have in common. Although useful, the id...
4. Part 4A. Can be scratched by a fingernail Amphibole asbestos White Made up of 1-2½ slender, flexible fibers that can be pulled apart Cerargyrite Shiny white or Appears waxy; 1-1½ gray...
5. Part 5A. Cannot be scratched by a fingernail but can be scratched by a copper penny Biotite (black mica) White Splits into thin, 2½-3 flat sheets that will bend without breaking B. Ca...
6. Part 6A. Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife Fluorite White Cleavage in 4 4 directions can give fragments that are shaped like octah...
7. Part 7Calcite is transparent or translucent, and—depending on the variety—its luster is glassy to earthy. Most calcite is white or colorless, but it can be a shade of pink, blue, gree...
8. Part 8Dolomite is abundant in the Llano uplift area of central Texas—particularly in the Cambrian and Ordovician rocks. A number of these central Texas dolomites have been quarried fo...
9. Part 9Another variety of gypsum is known as _fibrous gypsum_. It is made up of slender, brittle, needle-like fibers that fill the cracks in some rocks. If fibrous gypsum has a silky o...
10. Part 10In Val Verde County, the wad and pyrolusite are found mixed with soil, clay, gravel, sand, and plant remains. This material fills cracks in Lower Cretaceous limestones, it is sc...
11. Part 11A hard, compact, slightly translucent variety of cryptocrystalline quartz is called _jasper_. It commonly has a red, brown, or yellow color due to the presence of an iron oxide,...
12. Part 12In the Frasch method of sulfur mining, a well is drilled into the salt-dome cap-rock, and three pipes, one inside the other, are put into the well. Superheated water under press...
13. Part 13Balcones fault zone—a system of faults extending from north of Waco in McLennan County, through Travis and Bexar counties, to near Del Rio in Val Verde County (_see_ p. 42).
14. Part 14S salt (_see also_ halite): 40, 65, 66 domes: 43, 58, 64, 66, 91, 97 lakes: 66 rock: 40, 65 Salt Fork of the Brazos River: 43 sand: 41, 58, 72, 85, 91 blast: 86 building: 85 fil...