Weathering, Erosion and Decomposition

1. ,a mining technique in which the entire top of a mountain is removed with explosives
4. ,a mining technique that creates a large visible pit or hole in the ground
8. ,the least-weathered soil horizon
9. ,a soil horizon composed primarily of mineral material with very little organic matter
10. ,the proportion of soil bases to soil acids
12. ,the process of looking for minerals, metals and precious stones in river sediments
16. ,the breakdown of rocks and minerals by chemical reactions or the dissolving of chemical elements
17. ,the most fully decomposed organic matter in the lowest section of the o horizon
18. ,precipitation high in sulfuric acid and nitric acid from reactions between water vapor and sulfur and nitrogen oxides in the atmosphere
21. ,a concentrated accumulation of minerals from which economically valuable materials can be extracted
22. ,the mechanical breakdown of rock and minerals
23. ,a zone of leaching found in some acidic soils under the o horizon or the a horizon

2. ,frequently the top layer of soil
3. ,the removal of strips of soil and rock to expose ore
5. ,the organic horizon at the surface of many soils
6. ,the average concentration of an element in Earth's crust
7. ,mining techniques used when the desired resource is more than 100m below the surface of the Earth
11. ,the ability of a particular soil to absorb and release cations
13. ,unwanted waste material created during mining including mineral and other residues that re left behind after the desired metal or ore is removed
14. ,the loss of some or all of a soil's ability to support plant growth
15. ,the known quantity of a resource that can be economically recovered
19. ,a horizontal layer in a soil defined by distinctive physical features such as texture and color
20. ,an element with properties that allow it to conduct electricity and heat energy