raindrop imprint造句

• The sandy-mudstone beds including the Alderley beds are characterised by wavy laminae, desiccation cracks, mud flakes, raindrop imprints, loads and flutes.
• The air density dependence of the maximum raindrop diameter together with fossil raindrop imprints has been used to constrain the density of the air 2.7 billion years ago.
• He helped pioneer two techniques : using fossil raindrop imprints to set an upper limit on air density, which was applied to fossil imprints from 2.7 billion years ago, and using fossil bubbles in ancient lava flows, which suggests that air pressure 2.7 billion years ago was less than half that of the modern atmosphere.