moho discontiuity

The following statements are false but are perceived to be true by many people. Scientific hypotheses and theories are subject to revision on the basis of observations, improvements in technology, and continued scrutiny. Inevitably certain "truths" are reconsidered. This is how honest science works. Brief explanations follow each of the FALSE statements and web site links are provided for reinforcement and/or substantiation. For the few items in which there is controversy or clear disagreement, the scientific view is presented.

T. Ansel Toney
Professor of Earth Sciences (retired)
©1990; last revision May, 2007

Natural diamonds form in compressed coal.
Coal comes from ancient plant remains; most diamonds develop originally as crystals in very deep rock. All of the many natural diamonds that have been age-dated were created before coal formed on earth.
Crude oil is a mineral.
The geological definition of "mineral" requires that it be solid, inorganic, and crystalline. Crude oil is a viscous liquid made of organic compounds. Incidentally, crystalline means "atoms arranged in an orderly fashion." Why do you suppose oil is often called a mineral resource though it is not?
Tropical rainforest soils have relatively high inherent fertility.
They are among the poorest soils in the world. Leaching caused by the abundant rainfall rapidly removes basic nutrients.
Desert soils have poor potential fertility.
When irrigated, they are usually excellent though there are some special problems due to capillarity. In some relatively dry farming regions more water is used to "wash" the soil of salts than to irrigate.
Oil comes from the remains of dinosaurs.
It is believed that most oil formed from the remains of plankton, small aquatic organisms. Phytoplankton is the plant portion and zooplankton is the animal portion of the planktonic world.
Coral rock and limestone are not the same.
Actually, coral rock is a variety of limestone. Limestone is a calcium carbonate rock. Some other varieties of limestone are chalk, oolite, fossil, travertine, and when there is ample magnesium in the limestone, dolomite. Marble is metamorphosed limestone.
The Richter scale is the only standard for measuring earthquake magnitude.
Though the Richter scale measuring comparative motion is still used, many seismologists now prefer a more precise scale called the Moment Magnitude Scale. It indicates total energy released by an earthquake.
If a volcano does not produce lava it is not dangerous.
Many people have been killed by mudflows, and ash associated with volcanoes. In 1985 a mudflow (lahar) from Nevado del Ruiz in Colombia claimed over 25,000 lives. Deadly lahars are a problem in the Philippines. There is great concern that some of the volcanoes of the Cascades Range of the U.S. Northwest might produce catastrophic lahars (e.g. - Mt. Rainier which is 54 miles southeast of Seattle).
Water from our wells comes from underground rivers.
Though some Karst (limestone solutional) areas have small rivers that flow through cavern systems, most references to "underground rivers" are not to rivers in the conventional sense but to water flowing through pore spaces in rock layers beneath. These are sometimes called "aquifers". Water flows about 10' per day through the porous limestone of the Biscayne Aquifer beneath Miami-Dade County in Florida - very fast. A more typical rate is 10' per year.
Earth, below the lithosphere is almost entirely molten rock (magma).
The inner core is solid, the outer core is liquid, and the mantle is a solid. The latter is sometimes described as a semi-solid because it is has some plastic characteristics and is capable of extremely slow flowing - the rate being less than that at which your fingernails grow.