Iraj Maghfoori Moghaddam; Seyyed Aref Alavi
Volume 14, Issue 55 , November 2005, , Pages 17-21
Abstract
Living organisms are confronted with two different and opposing forces, one internal (genetic changes) and the other external (environmental changes). The outcome of this interaction is the evolution of organisms over time. The environmental changes that lead to the evolution of organisms can be divided ...
Read More
Living organisms are confronted with two different and opposing forces, one internal (genetic changes) and the other external (environmental changes). The outcome of this interaction is the evolution of organisms over time. The environmental changes that lead to the evolution of organisms can be divided into four groups: A. Ecological changes leading to Microevolution and natural selection become more or less stable in communities. B. Milankovitch cycles that cause severe changes in climate through cycles of twenty to one hundred thousand years, with the result of destruction of living communities and elimination of changes accumulated through ecological changes. C: Geological changes that cause the isolation of different populations of a species and cause major evolutionary changes (Macroevolution). D: Mass extinctions of organisms that averagely occur on the Earth every 26 million years and cause destruction of large groups of organisms in a very short time.
Iraj Maghfuri Moghaddam; Mahmoud Jalali
Volume 13, Issue 51 , November 2004, , Pages 23-26
Abstract
Like other natural phenomena of the universe, the inclination angle of the axis of the Earth is significantly variable. These changes can be divided into two groups. First, regular cyclic changes of the inclination angle of the Earth, which is part of the Milankovitch changes, and whose magnitude of ...
Read More
Like other natural phenomena of the universe, the inclination angle of the axis of the Earth is significantly variable. These changes can be divided into two groups. First, regular cyclic changes of the inclination angle of the Earth, which is part of the Milankovitch changes, and whose magnitude of positive and negative values in every 41,000 years are plus and minus 3.5. The second, long-term geological changes of the Earth's inclination angle, which seems to be one-sided and gradually decreasing since the beginning of the Phanerozoic Era (450 million years ago). Factors such as friction caused by tidal waves and separation of the Earth’s Flesh and Crust have contributed to this phenomenon. Long-term changes in the inclination angle of the Earth and its decrease have caused the formation of seasons as well as climatic division of geographic latitudes.
Iraj Maghfuri Moghaddam; Mahmud Jalali
Volume 11, Issue 44 , February 2002, , Pages 76-80
Abstract
Extinction is one of the important phenomena in the evolution of organisms. Extinction of a species occurs when organisms cannot adapt to sudden changes in the environment. The Earth is a very dynamic planet and resists many external changes leading to the stability of biological conditions. But in some ...
Read More
Extinction is one of the important phenomena in the evolution of organisms. Extinction of a species occurs when organisms cannot adapt to sudden changes in the environment. The Earth is a very dynamic planet and resists many external changes leading to the stability of biological conditions. But in some cases environmental changes are very severe. Among the most important factors of environmental changes is the collision of Meteorites to the surface of the Earth. In the early Cretaceous and the Late Eocene, the Earth was exposed to several Meteorites, which resulted in destruction of many creatures. In all Meteorites, the amount of iridium element is much higher than that of land deposits.Therefore, by finding more than the usual quantities of iridium on the Earth's layers, it can be held as possible that a Meteorite has hit the ground. Of course, it should be noted that in some cases the element of iodine accumulates in some sediments due to diagenetic factors.
