Complex sentence: For many years, the Solnhofen deposits were the only source of lithographic limestone, but shortly before 1867, quarries were opened in France near le Vigan, Gard and Cerin and Crey, Isère.
Split into simpler sentences: For many years, the Solnhofen deposits were the only source of lithographic limestone. Shortly before 1867, a second Lithographic Limestone quarry was opened in France near Cerin and Crey, Isère.