Alsace is primarily known for its white wines, though some red, rose, and sparkling wines are also produced. The grape varieties grown there are unique to the Alsace region. It has a semi-continental climate with hot summers and cold winters. The soils vary from sand to granite to clay. Alsace uses a classification system including Grand Cru for its highest quality wines, and designates wines by grape variety and sometimes vineyard. The main grape varieties grown are Riesling, Pinot Gris, Gewurztraminer, and Pinot Blanc.