This beach terrace marks an ancient shoreline of Summer Lake in south-central Oregon, the Oregon Outback
. During the ice ages, lakes occupied most of the wide, flat valleys in the Basin and Range province of the American west. Today those basins are mostly dry, many of them desolate playas
. But when the lakes existed, sediment from the land settled along the shorelines and created long, level beach terraces. Often several paleo-shoreline terraces appear on the basin's flanks, each one marking a former shoreline, or strandline
. Also, sometimes the terraces are distorted, yielding information about tectonic movements since the time they formed.
Strandlines along the seacoast may have similar raised beaches or wave-cut platforms.
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