MarlMarl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. Marl makes up the lower part of the cliffs of Dover, and the Channel Tunnel follows these marl layers between France and the United Kingdom. Marl is also a common sediment in post-glacial lakes, such as the marl ponds of the northeastern United States.
SilicosisSilicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust. It is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis. Silicosis (particularly the acute form) is characterized by shortness of breath, cough, fever, and cyanosis (bluish skin). It may often be misdiagnosed as pulmonary edema (fluid in the lungs), pneumonia, or tuberculosis. Using workplace controls, silicosis is almost always a preventable disease.
TinderboxA tinderbox, or patch box, is a container made of wood or metal containing flint, firesteel, and tinder (typically charcloth, but possibly a small quantity of dry, finely divided fibrous matter such as hemp), used together to help kindle a fire. A tinderbox may also contain sulfur-tipped matches. Tinderboxes fell out of general usage when friction matches were invented. Throughout prehistoric Europe flint and iron pyrites (commonly known as fool's gold) were struck against one another in order to create a spark for firelighting.
CristobaliteCristobalite (krɪˈstoʊbəˌlaɪt) is a mineral polymorph of silica that is formed at very high temperatures. It has the same chemical formula as quartz, SiO2, but a distinct crystal structure. Both quartz and cristobalite are polymorphs with all the members of the quartz group, which also include coesite, tridymite and stishovite. It is named after Cerro San Cristóbal in Pachuca Municipality, Hidalgo, Mexico. It is used in dentistry as a component of alginate impression materials as well as for making models of teeth.
Tool stoneIn archaeology, a tool stone is a type of stone that is used to manufacture stone tools, or stones used as the raw material for tools. Generally speaking, tools that require a sharp edge are made using cryptocrystalline materials that fracture in an easily controlled conchoidal manner. Cryptocrystalline tool stones include flint and chert, which are fine-grained sedimentary materials; rhyolite and felsite, which are igneous flowstones; and obsidian, a form of natural glass created by igneous processes.
Lithic technologyIn archaeology, lithic technology includes a broad array of techniques used to produce usable tools from various types of stone. The earliest stone tools to date have been found at the site of Lomekwi 3 (LOM3) in Kenya and they have been dated to around 3.3 million years ago. The archaeological record of lithic technology is divided into three major time periods: the Paleolithic (Old Stone Age), Mesolithic (Middle Stone Age), and Neolithic (New Stone Age).
Chopper (archaeology)Archaeologists define a chopper as a pebble tool with an irregular cutting edge formed through the removal of flakes from one side of a stone. Choppers are crude forms of stone tool and are found in industries as early as the Lower Palaeolithic from around 2.5 million years ago. These earliest known specimens were found in the Olduvai Gorge in Tanzania by Louis Leakey in the 1930s. The name Oldowan was given to the tools after the site in which they were excavated. These types of tools were used an estimated time range of 2.
MicrolithA microlith is a small stone tool usually made of flint or chert and typically a centimetre or so in length and half a centimetre wide. They were made by humans from around 35,000 to 3,000 years ago, across Europe, Africa, Asia and Australia. The microliths were used in spear points and arrowheads. Microliths are produced from either a small blade (microblade) or a larger blade-like piece of flint by abrupt or truncated retouching, which leaves a very typical piece of waste, called a microburin.
