منابع مشابه
Mechanisms of Abrupt Climate Change of the Last Glacial Period
[1] More than a decade ago, ice core records from Greenland revealed that the last glacial period was characterized by abrupt climate changes that recurred on millennial time scales. Since their discovery, there has been a large effort to determine whether these climate events were a global phenomenon or were just confined to the North Atlantic region and also to reveal the mechanisms that were...
متن کاملTiming and causes of North African wet phases during the last glacial period and implications for modern human migration
We present the first speleothem-derived central North Africa rainfall record for the last glacial period. The record reveals three main wet periods at 65-61 ka, 52.5-50.5 ka and 37.5-33 ka that lead obliquity maxima and precession minima. We find additional minor wet episodes that are synchronous with Greenland interstadials. Our results demonstrate that sub-tropical hydrology is forced by both...
متن کاملevaluation of sadr eminence in safavid period
چکیده: یکی از دوره های مهم تاریخی ایران به لحاظ تأمین استقلال ملی مذهبی و حتی تأثیر آن بر فرهنگ و مذهب ایرانیان، دوره صفویه است. رسمیت دادن و رواج مذهب شیعه توسط شاه اسماعیل اول، یکی از مهمترین اقدامات این دولت محسوب می شود. بنابراین برای اجرای این سیاست، وی منصب صدارت را به عنوان منصبی مذهبی- حکو متی ایجاد کرد .این منصب از دوره ی تیموریان ایجاد شده بود ولی در اواخر این دوره اهمیت بیشتری یافت...
15 صفحه اولLink between the North and South Atlantic during the Heinrich events of the last glacial period
High resolution benthic oxygen isotope records combined with radiocarbon datings, from cores retrieved in the North, Equatorial, and South Atlantic are used to establish a reliable chronostratigraphy for the last 60 ky. This common temporal framework enables us to study the timing of the sub-Milankovitch climate variability in the entire surface Atlantic during this period, as re#ected in plank...
متن کاملthe effect of taftan pozzolan on the compressive strength of concrete in the environmental conditions of oman sea (chabahar port)
cement is an essential ingredient in the concrete buildings. for production of cement considerable amount of fossil fuel and electrical energy is consumed. on the other hand for generating one tone of portland cement, nearly one ton of carbon dioxide is released. it shows that 7 percent of the total released carbon dioxide in the world relates to the cement industry. considering ecological issu...
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ژورنال
عنوان ژورنال: Scientific American
سال: 1884
ISSN: 0036-8733
DOI: 10.1038/scientificamerican03081884-6810supp