Jürgen Ehlers

This book provides a new look at the climatic history of the last 2.6 million years during the ice age, a time of extreme climatic fluctuations that have not yet ended. This period also coincides with important phases of human development from Neanderthals to modern humans, both of whom existed side by side during the last cold stage of the ice age. The ice age has seen dramatic expansions of glaciers and ice sheets, although this has been interspersed with relatively short warmer intervals like the one we live in today. The book focuses on the changing state of these glaciers and the effects of associated climate changes on a wide variety of environments (including mountains, rivers, deserts, oceans and seas) and also plants and animals. For example, at times the Sahara was green and colonized by humans, and Lake Chad covered 350,000 km2 – larger than the United Kingdom. What happened during the ice age can only be reconstructed from the traces that are left in the ground. The work of the geoscientist is similar to that of a detective who has to reconstruct the sequence of events from circumstantial evidence. The book draws on the specialisms and experience of the authors who are experts on the glacial history of the Earth. Readership: Undergraduate and postgraduate students studying the Quaternary, researchers, and anyone interested in climate change, environmental change and geology. The book provides a rich collection of illustrations and photographs to help the readers at all levels visualise the dramatic consequences of glacier expansions during the Ice Age.

This book provides a new look at the climatic history of the last 2.6 million years during the ice age, a time of extreme climatic fluctuations that have not yet ended. This period also coincides with important phases of human development from Neanderthals to modern humans, both of whom existed side by side during the last cold stage of the ice age. The ice age has seen dramatic expansions of glaciers and ice sheets, although this has been interspersed with relatively short warmer intervals like the one we live in today. The book focuses on the changing state of these glaciers and the effects of associated climate changes on a wide variety of environments (including mountains, rivers, deserts, oceans and seas) and also plants and animals. For example, at times the Sahara was green and colonized by humans, and Lake Chad covered 350,000 km2 – larger than the United Kingdom. What happened during the ice age can only be reconstructed from the traces that are left in the ground. The work of the geoscientist is similar to that of a detective who has to reconstruct the sequence of events from circumstantial evidence. The book draws on the specialisms and experience of the authors who are experts on the glacial history of the Earth. Readership: Undergraduate and postgraduate students studying the Quaternary, researchers, and anyone interested in climate change, environmental change and geology. The book provides a rich collection of illustrations and photographs to help the readers at all levels visualise the dramatic consequences of glacier expansions during the Ice Age.

The theory, observations, and applications ofgravitational lensingconstitute one ofthe most rapidly growing branches ofextragalactic astrophysics. The deflection of light from very distant sources by intervening masses provides a unique possibility for the investigation of both background sources and lens mass distributions. Gravitational lensing manifestsitselfmost distinctly through multiply imaged QSOs and the formation of highly elongated im­ ages of distant galaxies ('arcs') and spectacular ring-like images of extra­ galactic radio sources. But the effects of gravitational light deflection are not limited to these prominent image configurations; more subtle, since not directly observable, consequences of lensing are the, possibly strong, mag­ nification of sources, which may permit observation of intrinsically fainter, or more distant, sources than would be visible without these natural tele­ scopes. Such light deflection can also affect the source counts of QSOs and of other compact extragalactic sources, and can lead to flux variability of sources owing to propagation effects. Trying to summarizethe theory and observationalstatus ofgravitational lensing in a monograph turned out to be a bigger problem than any of the authors anticipated when we started this project at the end of 1987, encour­ aged by Martin Harwit, who originally approached us. The development in the field has been very rapid during the last four years, both through the­ ory and through observation, and many sections have been rewritten several times, as the previous versions became out of date.

"Mit goldenem Siegel" ist, wie der Untertitel "Uber Briefe, Schreiber und Boten im Sahname" aussagt, vor allem eine Untersuchung des Kanzleiwesens am vorarabischen persischen Konigshof, so wie es Ferdausi in seinem Werk geschildert hat. Da allgemein angenommen wird, dass der Dichter sich bis in die Schilderung von Details an seine Vorlagen gehalten hat, erhalt die Darstellung der Arbeit von koniglichen Ratgebern, Sekretaren und Schreibern grosse kulturhistorische Bedeutung. Im Buch werden auch die Arbeitsmittel der Schreiber, das Entstehen von Briefen wie auch die vielfaltigen Aspekte der Briefzustellung durch Boten dargestellt, wobei in Fussnoten auf Parallelen bei anderen zeitgenossischen Autoren und auf Literatur zu den verschiedenen Themen der Untersuchung hingewiesen wird. Zu diesen Themen bringt der Autor exemplarisch Passagen von verschiedener Lange aus dem Sahname in eigener Ubersetzung. Ein Teil des Buches wird durch die Untersuchung von Inhalt und Stil der rund 260 Briefe eingenommen, die am Schluss vor den Stichwortverzeichnisen aufgelistet sind. In einem eigenen Kapitel werden eine Reihe der schonsten bzw. wichtigsten dieser Briefe in Ubersetzung vorgestellt. Das Schlusskapitel beschaftigt sich im Rahmen des Themas mit den noch vorhandenen eventuellen Vorlagen und ihrer Beziehung zu Ferdausi. Der Arbeit vorangestellt ist ein Vorwort von Djalal Khaleghi-Motlagh, dem Herausgeber der neuen kritischen Sahname-Ausgabe.

Mit zahlreichen bisher unveröffentlichten historischen und aktuellen Aufnahmen.

The Wadden Sea area of the North Sea is one which undergoes rapid morphological changes. Under natural conditions, the barrier islands would adjust them¬selves to a rising sea level. However, be¬cause the islands are densely populated and have an important role as holiday resorts, morphological changes are un¬desirable. Coastal engineering counter-measures have been undertaken to pre¬vent beach erosion, shifting of tidal in¬lets, breaching of dune ridges and land¬ward-directed washover. The natural processes and the results of human inter¬ference including the negative conse¬quences of many of the measures are discussed in detail. The author presents the current state of research, together with the results of his own investigations. In addition, a comprehensive description of the geomorphological development and recent problems of the barrier is¬lands from Texel to Fanø is given for the first time. The book includes 40 colour photographs and 393 figures, almost all previously unpublished. Sat¬ellite and radar imagery as well as many aerial photographs are also included. The book is intended for geomorphologists, sedimentologists, environmentalists and all those with a scientific interest in tidal flats and barrier islands.