Early Cretaceous


Late Cretaceous



Isotopical Evidence




Climate Change Home Page

KT Event

Back to
Bristol Palaeontology


Albedo:the ratio of the amount of solar radiation reflected from an object to the total amount incident upon it. An albedo of 1.0 indicates a perfectly reflecting surface, while a value of 0.0 indicates a totally black surface that absorbs all incident light. The albedo of earth is calculated as 0.39, more than half of which is due to reflection from clouds.

Ammonite:a marine organism with a coiled hard shell, that lived from the Lower Devonian and were extinct by the end of the Cretaceous Period.

Angiosperm:plants that possess true flowers with seeds enclosed in an ovary.

Belemnite:an extinct (in early Tertiary) marine organism with a cone-shaped shell.

Benthic:those organisms that live on the sea floor

Chalk:a soft, earthy, fine-grained white to greyish limestone of marine origin. It is composed almost entirely of by shallow-water accumulations of coccoliths and other forams and forms in a sea predominantly free from terrigeneous sediment.

Climate:the average weather of a place, together with the degree of variability of that weather , over a period of time.

Coccolith:a small marine photosynthetic foram found only in warm, low-latitude waters.

Cretaceous:the interval of geological time that began about 140 million years (Ma) ago, and lasted about 75 Ma to the KT boundary 65 Ma ago. It is the final period of the Mesozoic Era, and precedes the Tertiary Period.

Equable Climate:Very little contrast between the climate at the equator from that at the poles. This was thought to be so during the Mid to Late Creatceous and is not so today.

Foram:(short for foraminifera) tiny sea living organism that excretes a shell of calcium carbonate.

Goddard:an extinct single celled organism, that was able to articulate on a layer of slime excreted from its cell membrane.

Gondwanaland:the southern protocontinent land mass that was derived from the supercontinent Pangaea. It was thought to have comprised of Antarctica, Africa, South America, Australia and India.

Hot spots:are thought to be due to rising plumes of hot rock from the mantle, such as that thought to exist beneath Hawaii.

Incidence of light:the amount of light penetration into the oceans.

Isotope:a particular atom of an element that has the same atomic number, but a different atomic mass. Since the chemical properties of an element are determined by the atomic number, isotopes of an element have essentially the same chemical properties as the other atoms. For example O16 and O18 are stable isotopes of oxygen. Unstable isotopes, such as isotopes of Uranium, are used in the nuclear power industry.

Laurasia:the northern protocontinent that was derived from Pangaea. It comprised of North America, Eurasia (exclusive of India) and Greenland.

Magma:molten, mobile rock material that is naturally occurring.

Mesozoic:the Mesozoic ('middle life') Era was a span of geological time between 250 and 65 Ma. It included the Triassic, Jurassic and Cretaceous periods.

Mid-oceanic ridge:the volcanic mountain range beneath the oceans where new oceanic crust is being created by eruption of magma. For example, the Mid-Atlantic Ridge.

Palaeontology:the study of life forms that existed in past geological periods, as represented by fossil plants and animals.

Planktic:free-floating and drifting organisms that live in the water column.

Shale:a fine-grained sedimentary rock formed by the compaction of silt, clay, or sand that accumulates in deltas and on lake and ocean bottoms.

Tethys:the sea that separated Gondwanaland from Laurasia.

Tillite:a sediemntary rock formed by the compaction of till. Till is generally non-stratified, poorly sorted material deposited directly by glacial ice.

Volcanism:processes of the discharge of molten or hot rock or hot water at the surface of the Earth.



| Intro | Early Cretaceous | Mid-Cretaceous | Late Cretaceous |

| Palaeontological Evidence | Sedimentological Evidence | Isotope Evidence |

| Summary | Glossary | Further Reading | Climate Change Home Page | KT Event Links | Back to Bristol Palaeontology Homepage |