H. H. WALES. LADO SUR DE LA ALAMEDA. CALLE DE LA ARTILLERIA Hotel Internacional S. L. P. No. 6. San Luis Potosi, de 190 The Tertiary plain must have an elevation of nearly 400 feet and the train seemingly rises fully another 400 feet before encountering the first Cretaceous wall. After one has risen onto the Tertiary Plain one sees no farms, habitation or streams. But as one proceeds east on the undulating Plain and near to the Cretaceous wall, i.e. about 3 kilometers east of Balles (142 Kil.) we pass over a dirty stream leading to one high vertical cliff of 700 m height. These trees dip as much as cypresses. These also are probably Tertiary as they do not have the steep or vertical dips of the Cretaceous. Further west rising into these old Tertiary trees the country is much hilly. The water along the western side of the Tertiary Plain must sink through these rocks and issues as fresh springs at the base of the Tertiary as was actually seen in my case and describing above. Just before one arrives at Balles (139 Kil. east of Tampico) one gets one first view, to the left, of the first Cretaceous wall. It is entirely unlike the Tertiary are being very much dissected, and having moreover the look of a hub of A little north of Miccos (164 Kil.) we begin to rise on the Cretaceous through the dips and rapidly falling rapids of Miccos. They are to our right a series of fan shaped falls and rapids. The Cretaceous rocks here all stand on end or so nearly on end as to appear so and on our right, the opposite side of Miccos Falls stand in cliffs of 700 feet. Took a picture of the falls and have one for Mr. Brown.