Straight up through the center of this mountainous area are projected a series of more or less parallel limestone ridges. These, as a rule, have an east and west axis, and attain a greater elevation than the lomas. They are known as the Sierras de los Organos, although having many local names at different points. Water and atmospheric agencies have carved them into most fantastic shapes, so that they do, in places, present an organ pipe appearance. They are almost always steep, often with vertical walls or "paradones" that rise 1,000 feet from the floor or base on which they rest.
The northernmost range, running parallel to the Gulf Coast, is known as the "Costanero." The highest peak of Pinar del Rio is called Guajaibon, which rises to an altitude of 3,000 feet, with its base but very little above the level of the sea. It is probably of Jurassic limestone and forms the eastern outpost of the Costaneros.
The southern range of the Organos begins with an interesting peak known as the Pan de Azucar, located only a few miles east of the Pena Blanca. From this western sentinel with many breaks extends the great southern chain of the Organos with its various groups of "magotes," reaching eastward throughout the entire province. At its extreme eastern terminus we find a lower and detached ridge known as the Pan de Guanajay, which passes for a few miles beyond the boundary line, and into the province of Havana.
Surrounding the Organos from La Esperanza west, and bordering it also on the south for a short distance east of the city of Pinar del Rio, are ranges of round topped lomas, composed largely of sandstone, slate and shale. The surface of these is covered with the small pines, scrubby palms and undergrowth found only on poor soil.
From the Mulato River east, along the north coast, the character of the lomas changes abruptly. Here we have deep rich soil covered with splendid forests of hard woods, that reach up into the Organos some ten miles back from the coast. Along the southern edge of the Organos, from Herredura east, lies a charming narrow belt of rolling country covered with a rich sandy loam that extends almost to the city of Artemisa.
Extensions, or occasional outcroppings, of the Pinar del Rio mountain system, appear in the Province of Havana, and continue on into Matanzas, where another short coastal range appears, just west of the valley of the Yumuri. This, as before stated, has its continuation in detached ranges that extend along the entire north coast, with but few interruptions, until merged into the mountain maze of eastern Oriente.