Three water-filled maars in the Eifel, Germany
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Deprecated function: strtotime(): Passing null to parameter #1 ($datetime) of type string is deprecated in extra_body_classes_preprocess_html() (line 105 of modules/extra_body_classes/extra_body_classes.module).
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call_user_func_array('extra_body_classes_preprocess_html', Array) (Line: 261)
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Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object, 'kernel.view') (Line: 186)
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Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object, 1, 1) (Line: 704)
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Three water-filled maars in the Eifel, Germany (Gemündener Maar, Weinfelder Maar, Schalkenmehrener Maar). Created by volcanic activity, maars are also found in other parts of Europe and on other continents, but Eifel-Maars are the classic example worldwide.
Martin Schildgen / Wikimedia Commons
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