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During the Last Glacial Maximum, [5] (between about 26,000 and 20,000 years BP) ice sheets more than 3,000 m (9,800 ft) thick scoured the landscape of Ireland. By 24,000 years ago they extended beyond the southern coast of Ireland; but by 16,000 years ago the glaciers had retreated so that only an ice bridge remained between Ireland and Scotland.
This is a list of the oldest-known trees, as reported in reliable sources. Definitions of what constitutes an individual tree vary. Definitions of what constitutes an individual tree vary. In addition, tree ages are derived from a variety of sources, including documented "tree-ring" ( dendrochronological ) count core samples, and from estimates.
These were locally available as they were traditionally used to probe for prehistoric fallen timber below the bog.) [7] The ensuing excavation of habitation sites and tombs revealed the way of life of people living 200 generations earlier. [7] They were a community of farmers who cleared large areas of forest for use as farm land. [7]
Prehistoric Ireland's Later Mesolithic period begins sometime between 7000 BC and 6000 BC with the occurrence of a pan-Ireland and Isle of Man macrolithic (large stone flake/blade) stone tool tradition: no transitional industry has yet been identified that bridges the gap between this industry and the Early Mesolithic microlithic (very small flake/blade) industry that preceded it.
The site was discovered by George Barnett [5] [6] in the late 1930s during peat cutting when 1,269 stones were uncovered, [2] and partially excavated in 1945–1949 when it was taken into state care. It was also excavated again in 1965. Hearths and deposits of flint tools were discovered and have been carbon dated to 2900-2600BC.
Before the Quaternary glaciations the Irish landscape had a thick weathered regolith on the uplands and karst in the lowlands. Pre-Quaternary relief was more dramatic than today's smoothed landforms. [15] Since about 1.7 million years ago, the Earth has been subjected to a cycle of warm and cold stages and these have, inevitably, affected Ireland.
The 2nd-century Alexandrian Greek writer Ptolemy, one of the most important geographers, mathematicians and astronomers in the ancient world, refers to Ireland in two of his works. In the astronomical treatise known as the Almagest he gives the latitudes of an island he calls Mikra Brettania (Μικρὰ Βρεττανία) or "Little Britain ...
Archaeopteris is a member of a group of free-sporing woody plants called the progymnosperms that are interpreted as distant ancestors of the gymnosperms. Archaeopteris reproduced by releasing spores rather than by producing seeds, but some of the species, such as Archaeopteris halliana were heterosporous, producing two types of spores.