PHILLIPS is referring to an exceptionally cold period, which was especially acute in the temperate zones, and is believed to be cyclic ' a recurring phenomenon. It last occurred, according to some investigators, roughly between the sixteenth and the nineteenth centuries (that is, between the 1500s and the 1800s).But not all sources accept these dates. Krishna Ramanujan, of NASA's Goddard Space Flight Centre, for instance, puts the onset at 'the early 1400s' and the culmination in the 'late 1800s'.'The Little Ice Age,' notes the Environmental History Resources website, 'is a period between about 1300 and 1870 during which Europe and North America were subjected to much colder winters than during the 20th century.'Actually, the dates when the Little Ice Age began and ended depends, to a very large extent, on the criteria one uses. Wikipedia points out, for example, that ice masses in the North Atlantic began to increase as early as 1250, while, in Northern Europe, summer stopped arriving on schedule in 1300.Although parts of Europe were racked by heavy rains and great famine in 1315, it was, theorists believe, in 1550 that world-wide glacial expansion commenced: Glaciers being great sheets of ice (up to three km thick) that descend from continental mountain tops and push towards the equator from Earth's poles.But while sources may dicker over the dates, there is more or less general agreement that temperature fluctuations coincided with highs and lows of solar activity, particularly the sunspot cycle. Thus the 70-year Maunder minimum is also a temperature minimum ' the peak of the Little Ice Age.It needs to be stressed, at this juncture, that 'Little Ice Age' is merely a term of convenience. Scientifically and historically, it is something of a misnomer. What occurred during this period was not, in fact, an 'ice age'.During a true ice age, great glaciers rumble down from their elevated heights, gorging valleys between the bases of mountains, carving granite as if it were corkwood and leaving the landscape strewn with gargantuan boulders as they retreat.These glaciers advance and retreat in approximately 100,000-year cycles, called glacials and interglacials. 'In fact,' notes the Encyclopaedia Britannica Online, 'the Earth system has alternated between glacial and interglacial regimes for more than two million years, a period of time known as the Pleistocene.'On average, geologists have found, an interglacial (warm period) lasts for about 11,000 years. Presently, Britannica continued, 'Earth is'within the most recent interglacial period, which started 11,700 years ago and is commonly known as the Holocene Epoch ...'Thus far, investigators have identified five important icing events (of varying magnitudes) in Earth's geological history and a number of lesser glacial episodes'starting with the Huronian Ice Age (2.4 to 2.1 billion years ago).The seminal Cryogenian followed (consisting of at least three glaciations - 750-600 M.Y.A.), during which it is believed that advancing ice sheets reached the equator 'which could, conceivably, explain the beautiful boulder-studded landscape of Northern Nigeria and parts of the West.But a caveat ought to be casted in: Geologically, Nigeria has not always been a part of Africa. It joined the continent after drifting in from the South Pole, along with the rest of the West African landmass!To be continued.
Click here to read full news..
