After reading the respective note use the back-arrow of your browser to continue reading the article. You may also go to the individual chapters using the links at bottom of this page.
You may also browse the Scientific Annotations (which are designed for scientists but might nevertheless be of interest to you)
- REEFS: In geology and biology reefs are composed of bodies made of calcium carbonate (limestone) which is derived from sessile organisms precipitating carbonate skeletons, such as corals and many calcareous algae. Normally reefs exhibit a more or less pronounced morphology. Young, immature reefs are often laterally extensive but may not have a positive morphology. We call them reef meadows in this article. Submarine cliffs of other origin (for example, uplifted granitic rocks) which might endanger ship traffic, are frequently referred to as 'reefs' in colloquial language but are not reefs in the scientific sense.
- JURASSIC, CRETACEOUS etc.: Time period expressions such as Jurassic or Cretaceous are used to name the time-episodes of the Earth's history and set up a geological time scale. Relative ages of these time-'periods' (and further subdivisions, such as 'epochs' or 'ages') are well established, mostly by using fossils such as ammonites). Rocks of a certain 'Period' are known as 'Systems' (hence: rocks formed during the Jurassic Period represent the Jurassic System). Absolute ages are more difficult to calculate, and this is why you may find differing ages in different time scale, depending on the method used. Here is the entire geological time scale or more information on the Jurassic Period.
- MICROBES: Microbes are all organisms which are visible only with the microscope. They include microscopic algae and bacteria (amongst others). Microbial films or (if better developed) microbial mats are very widespread (- microbial films even exist on our teeth). They are produced by bottom-dwelling algae (diatoms) and bacteria (both photosynthetic forms, that is plant-like, using sunlight for production of organic matter; and so-called heterotrophic forms, that is animal-like, using already existing organic matter to feed on). These bacteria produce a lot of organic, sugar-like matter (films) which provide a food stock for bad times and serve to stabilize the microenvironment needed for the microbes to grow. When films are continuously produced, they thicken and may form fairly stable microbial mats which easily calcify in warm tropical waters.
- TETHYS: The Tethys was the large East-West seaway existing (in different configurations) from the Paleozoic to the Early Cenozoic. In the late Paleozoic and early Mesozoic it was a semienclosed large ocean basin extending from the Palaeo-Pacific westwards into the supercontinent Pangaea. View an image of the configuration of the Tethys in the Late Jurassic world (8 kb) or wait for Chapter V to find out more about the Tethys. If you cannot wait, go straight to Chapter V (Jurassic Period).
Last changes 18. Nov. 98 by Reinhold Leinfelder