Table of Contents
What is expansive shale?
Introduction. Expansive strata are soil and/or rocks that contain clay minerals that have the potential for swelling and shrinkage under changing moisture conditions. Clay minerals could originate from the weathering of shale, slate, sandstone, and limestone.
What type of rock is shale?
Shale rocks are those that are made of clay-sized particles and are have a laminated appearance. They are a type of sedimentary rock. Shale is the abundant rock found on Earth. They are usually found in areas where gentle waters have deposited sediments that become compacted together.
How did shale form over time?
Shale forms via compaction from particles in slow or quiet water, such as river deltas, lakes, swamps, or the ocean floor. Heavier particles sink and form sandstone and limestone, while clay and fine silt remain suspended in water. Over time, compressed sandstone and limestone become shale.
What is shale used for today?
Shale is commercially important. It is used to make brick, pottery, tile, and Portland cement. Natural gas and petroleum may be extracted from oil shale.
Why is shale so common?
Is shale older than sandstone?
Using Figure 11.4, answer the following questions concerning the relative ages of the features illustrated. Also, when indicated, list the law or principle of relative dating you used to arrive at your answer. b) The shale is [older, younger) than the sandstone.
How much oil shale is there compared with the rest of the world?
It is estimated that there are at least 8 trillion barrels of oil shale resource around the world (6). Countries are ranked according to the respective volumes of oil shale resource in place. The United States’ oil shale resources surpass all other countries with an estimated 6 trillion barrels of resource in place.
What happens to pyritic fill?
Fills of pyritic materials are particularly subject to accelerated weathering and heaving. Alteration has been noted to a depth of 3 feet in originally sound pyritic shale over a 10-year period in Ottawa: and there are reports in the literature of weathering to a depth of 10 feet during the lifetime of a building.
Can bacterial oxidation of pyrite cause heaving problems?
Bacterial oxidation of pyrite is also known to occur in massive non-layered noncalcareous rocks. The likelihood of its causing severe heaving problems under buildings in these circumstances is less because the most severe expansion seems to occur when layers of the rock are forced apart by growth of gypsum (Figure 3).
Why is weathering of pyrite particularly destructive?
Weathering of pyrite is particularly destructive because of the attendant volume and stress increases that occur with oxidation and the chemical reactions that follow between the oxidation products and other components of pyrite bearing strata.
Is pyrite a biological or chemical change?
The weathering of pyrite is a chemical-micro-biological oxidation process; some of the oxidation reactions are believed to be solely chemical, others are attributed to autotrophic bacteria of the Ferrobacillus-Thiobacillus group (Figure 2), and still others are both chemical and micro- biological.