CHAPTER II. HAVANA TO VERA CRUZ—VERA CRUZ TO MEXICO.

on the outskirts of the Mexican valley. Besides this, traces of more recent volcanic action abound, in the shape of numerous extinct craters in the high plateaus, and immense “pedrigals” or fields of lava not yet old enough for their surface to have been disintegrated into soil. Though sedimentary rocks occur in Mexico, they are not the predominant feature of the country. Ridges of limestone hills lie on the slopes of the great volcanic mass toward the coast; and at a still lower level, just in the rise from the flat coast-region, there are strata of sandstone. On our road from Vera Cruz we came upon sandstone immediately after leaving the sandy plains; and a few miles further on we reached the limestone, very much as it is represented in Burkart’s profile of the country from Tampico upwards towards San Luis Potosi. The mountain-plateaus, such as the plains of Mexico and Puebla, are hollows filled up and floored with horizontal strata of tertiary deposits, which again are covered by the constantly accumulating layers of alluvium.