Chalk Totally Explained

Everything about Chalk totally explained

Chalk is a soft, white, porous sedimentary rock, a form of limestone composed of the mineral calcite. It forms under relatively deep marine conditions from the gradual accumulation of minute calcite plates (coccoliths) shed from micro-organisms called coccolithophores. It is common to find flint and chert nodules embedded in chalk.
   Chalk is relatively resistant to erosion and slumping compared to the clays with which it's usually associated, thus forming tall steep cliffs where chalk ridges meet the sea. Chalk hills, known as chalk downland, usually form where bands of chalk reach the surface at an angle, so forming a scarp slope. Because chalk is porous it can hold a large volume of ground water, providing a natural reservoir that releases water slowly through dry seasons.
   Chalk has been quarried since prehistory, providing building material and marl for fields. In southeast England, deneholes are a notable example of ancient chalk pits.
   The Chalk Formation is a European stratigraphic unit deposited during the late Cretaceous Period. It forms the famous White Cliffs of Dover in Kent, England. The Champagne region of France is mostly underlain by chalk deposits, which contain famous caves beneath the hills.

Chalk uses

The traditional uses of chalk have in many cases been replaced by other substances, although the word "chalk" is often still applied to the replacements.

Blackboard chalk is a substance used for drawing on rough surfaces, as it readily crumbles leaving particles that stick loosely to these surfaces. Although traditionally composed of natural chalk, modern blackboard chalk is generally made from the mineral gypsum (calcium sulfate), often supplied in sticks of compressed powder about 10 cm long.

In agriculture chalk is used for raising pH in soils with high acidity. The most common forms are CaCO₃ (Calcium carbonate) and CaO (Calcium Oxide).

In lawn tennis, powdered chalk was used to mark the boundary lines of the court. This gives the advantage that, if the ball hits the line, a cloud of chalk or pigment dust can be seen. Nowadays the substance used is mostly titanium dioxide.

In gymnastics, rock-climbing, bouldering, weight-lifting and tug of war, chalk—now usually magnesium carbonate—is applied to the hands to prevent slipping.

Tailor's chalk is traditionally a hard chalk used to make temporary markings on cloth, mainly by tailors. Nowadays it's usually made from talc (magnesium silicate).

Sidewalk chalk is made of sticks of colored chalk (now mostly gypsum) used to draw on sidewalks, streets, and driveways. It is often done by children, but in many cities, talented adult artists create masterpieces on the walkways.

Toothpaste also commonly contains small amounts of chalk.Further Information

Get more info on 'Chalk'.

External Link Exchanges

Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:

<a href="http://chalk.totallyexplained.com">Chalk Totally Explained</a>

Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned.