Any period of extensive glaciation (in which icesheets and icecaps expand over the Earth) occurring in the Earth's history, but particularly that in
An iceberg is a very large piece of freshwater ice floating in a body of water. Icebergs are formed through the process of calving, when the front
Rocks formed by the cooling and solidification of molten magma , either below the Earth’s surface as intrusions , or at the surface through volcanic
A deposit of a pyroclastic flow . Because of confusion in past use, the term is best restricted to deposits rich in pumice . Some of the largest
( ĭgwä'nə ), name for several large lizards of the family Iguanidae, found in tropical America and the Galapagos. The common iguana (Iguana iguana) is
The adaptable system of body defences centres on specialized white blood cells called lymphocytes. These respond to invasion by varied microorganisms.
The body's defence against foreign substances such as bacteria, viruses and parasites. Immunity also protects against drugs, toxins and cancer cells.
Process of conferring immunity or resistance to an infectious disease by artificial methods, usually by the administration of a vaccine . Immunization
In the late 18th century Dr. Edward Jenner stumbled upon the notion of the immune system following his discovery that cowpox protected him against a
any of a variety of substances used to prevent production of antibodies . They are commonly used to prevent rejection by a recipient's body of an