The martian hemispheric dichotomy may be due to a giant impact

  title={The martian hemispheric dichotomy may be due to a giant impact},
  author={Don E. Wilhelms and Steven W. Squyres},
Mars is divided into two fundamentally different geological provinces of approximately hemispherical extent1–3. The more southerly province is heavily cratered, contains relatively old geological units, and superficially resembles the lunar and mercurian highlands. The northern province is relatively lightly cratered and contains younger geological units, including extensive plains, volcanic edifices, and volcanic calderas. Except for the Tharsis and Elysium regions and other large volcanoes… 
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