Massive Australian Precambrian/Cambrian Impact Structure Massive Australian Precambrian/Cambrian Impact Structure The Massive Australian Precambrian/Cambrian Impact Structure also known as MAPCIS is a proposed impact structure based upon arguments presented by Daniel P. Connelly at Geological Society of America meetings. Its center is located approximately equidistant between Uluru (Ayers Rock) and Mount Conner in Australia's Northern Territory. The structure is approximately in diameter. However, a hypothetical outermost ring in diameter is claimed to be the result of undefined far field stresses. Connelly argues that the age of this hypothetical impact is approximately 545 mya which puts it just before the Cambrian explosion (542 mya) of the
Local attraction Local attraction While compass surveying, the magnetic needle is sometimes disturbed from its normal position under the influence of external attractive forces. Such a disturbing influence is called as local attraction. The external forces are produced by sources of local attraction which may be current carrying wire (magnetic materials) or metal objects. The term is also used to denote amount of deviation of the needle from its normal position. It mostly causes errors in observations while surveying and thus suitable methods are employed to neglect these errors. The sources of local attraction may be natural or artificial. Natural sources include