https://rajpub.com/index.php/jns/issue/feed JOURNAL OF ADVANCES IN NATURAL SCIENCES 2020-07-27T04:44:19+00:00 Gurpal Kaur editor@rajpub.com Open Journal Systems https://rajpub.com/index.php/jns/article/view/8832 Northward shifts of Canadian late deglacial drainage routes caused a stronger and warmer Canaries Current that enabled Holocene monsoons and a savanna on the western Sahara 2020-07-27T04:44:19+00:00 Robert G. Johnson glenjay@bitstream.net <p>This paper proposes an explanation for the well-watered savanna on the presently barren western Sahara Desert during the mid-Holocene and near the ends of other earlier Canadian deglaciations. Between 7,500 and 4,000 years before present, a humidity index indicates moist conditions and a savanna in the western Sahara. During this interval, a stronger and warmer Canaries Current return flow of the Gulf Stream nullified the effect of cold water that upwells off the northwest African coast due to the westward movement of surface water by trade winds. The return flow was stronger than today because less eastward Gulf Stream flow was lost to the northward flow of the Atlantic Meridional Overturning Current. The Canaries Current was warmer than today because cold southern Canadian meltwater no longer entered the Gulf Stream, and the high latitude climate was warmer then. Similar conditions probably prevailed at the ends of many other deglaciations, which were separated by 20,000 to 70,000 years due to orbital factors and variable glaciation. The savanna connections across the Sahara would have allowed each Hominin population to evolve in the isolated Moroccan-Algerian coastal zone to extend its range into the larger Africa. The intermittent savannas could therefore have played a significant role in the evolution of the many Hominin species found in the African fossil record over the last three million years.</p> 2020-09-28T00:00:00+00:00 Copyright (c) 2020 Robert G. Johnson https://rajpub.com/index.php/jns/article/view/8616 The Research of the Radial Growth of the Flora Species Which Do Not Have Special Protection on the South Hillsides of Greater Caucasus 2020-02-15T03:40:23+00:00 Prof. RAE. Z.H. Aliyev zakirakademik@mail.ru <p>The radial growth of the trunks of the following flora species which do not have special protection on the southern hillsides of Greater Caucasus was studied in the article: Georgioan oak- <em>Quercus iberica</em> M.Bieb Common hornbeam - <em>Caprinus betulus</em> L. Common chestnut - <em>Castanea sativa</em> Mill. Black walnut - <em>Juglans nigra</em> L., Heart leaved alder - <em>Alnus subcordata</em> C.A.Mey. During the dendrochronological analyses, the dynamics of growth over the years were analysed based on the distances between the tree rings. The impact of the climatic factors on the growth of the trees was analysed and the ages of tree species were investigated.</p> <p>Based on the dendrochronological historical application, according to the numbers of tree rings, the ages of the trees were defined in the studied species. According to the numbers of tree rings, the oldest type of the rare and scanty flora types which have no special protection was identified as <em>Caprinus betulus </em>L. in the Zagatala region. The tree was taken from Zagatala district, planted in 1944, was 75 years old and had 330 cm diameter. The observation of dendrochronological researches indicates the formation of a new microclimate. It was observed that in the investigated species, radial growth was more intense during matureness, then it was weakened with age. In the comparative analysis, it was observed that the minimum radial growth was in 2010 and 2015, and the maximum growth was between 1973 and 1985 in the Zagatala region</p> 2020-01-25T00:00:00+00:00 Copyright (c) 2020 Prof. RAE. Z.H. Aliyev