We have been looking at geology for quite some time and have moved into sedimentary rock. LR found chalk to be very interesting and began researching it. Here is his report. This semester we are putting great emphasis on citing works – footnotes to be added during future papers.
Chalk is a sedimentary and a type of limestone. It is made of calcite (CaCO3). It is formed usually underwater. The calcite comes from the exoskeletons from micro-organisms called coccolithophores. Most of the calcite deposits are from the Cretaceous Period. Chert or flint is often found in chalk. Chalk is resistant to wind erosion compared to other clays. When wind erodes sedimentary rock above the chalk, it leaves large open masses of chalk. Chalk is mainly found in Europe. One example of popular deposits of chalk is the White Cliffs of Dover in Kent, England. In the Champaign Region of France, the natural underground chalk caves are used for wine-cellars.
During WWI and WWII some wine-cellars and subways were as makeshift bunkers. These caves are 60 feet underground. In 1917 during WWI, a group of 24,000 French soldiers hid in these caves for eight days until the Battle of Arras in the region of Artois. The walls are covered in graffiti from the soldiers. One soldier carved a thanksgiving in the wall saying, “Thanks be to God for providing us with this shelter from shells and bullets.” Shortly during WWII the caves were used as an air raid shelter. Later on an area of 820 feet of the Grange Subway at Vimy Ridge opened to the public from May through November. The Wellington tunnel was opened to the public as the Carrière Wellington museum in March 2008.
Chalk has been used for other things than bomb shelters. When chalk is converted into quicklime a fuel for limekilns, limekilns provided heat for cooking and to make plaster. Chalkboard Chalk is used for writing on chalkboards. Today’s chalk is made of gypsum. Sidewalk chalk is similar to chalkboard chalk, but is larger and usually is colored and is used on sidewalks. Agricultural chalk is used to lower the ph or the high acid levels of the fields. Chalk is also used to paint lines on soccer fields, grass tennis fields, etc. To reduce slipping in rock climbing, gymnastics, and weight lifting chalk is applied to the hands. Tailor’s chalk is used to make markings on cloths, but is now replaced with talc. Chalk is used to reduce pollutants in coal power plants.
Chalk is used everyday, but is being replaced by other minerals in the past decades. It’s softness it many used in very different situations. It has sheltered soldiers in the time of war and taught children across the world. It is one of the most interesting minerals on Earth.
L.F Salzman English Industries of the Middle Ages New Edition Enlarged and Illustrated, Oxford at the Clarendon Press 1923, Printed in England.
Ed. Gerald V. Middleton Encyclopedia of Sediments and Sedimentary Rocks, Copyright 2003 Kluwer Academic Publishers 3300 AA Dordrecht, The Netherlands.