Territorially Guatemala has its central and most important areas in the reliefs which, generally directed from E to W, represent a section of the long chain that continues from Mexico to Panama. On the northern side, Guatemala includes a section of the large tabular surfaces of the Yucatán (the Petén), on that of the Pacific, finally, the short coastal selvedge constitutes the third morphological element of the country. The central mountain section has a complex structure. It originated following the crustal movements that, in the Cenozoic, led to the establishment of the Central American isthmus. The first orogenetic phase was the birth of the northern chains that dominate the Caribbean side, namely the Altos Cuchumatanes (3993 m), the Sierra de Chuacús (2651 m), the Sierra de las Minas (3140 m), etc.: this is of blocks fractured and raised with respect to the Yucatán platform, formed by paleozoic rocks and intrusive granite masses. This origin assures to this mountainous section lines that are never very harsh, on the contrary sometimes stretched out to plateau. These reliefs are juxtaposed with the volcanic cordillera, a more recent corrugation that dominates the Pacific side, formed by a crystalline substrate surmounted by volcanic expansions and, morphologically, by an uninterrupted series of volcanic cones and craters. This is where Guatemala takes on its most distinctive aspect.
According to itypeusa, this “external” wrinkle, separated from the northern reliefs by a well marked tectonic groove (upper basin of Motagua), it has a continuous course, but is broken by small depression basins, formed following longitudinal fractures. The basins themselves, tectonically tormented areas, are crowned by the aforementioned volcanic cones, some of which are still active. Starting from the Mexican border, they meet the Tacaná (4093 m), the Tajumulco (4220 m), the Santa María (3772 m), the Atitlán (3537 m) overlooking the lake of the same name, the Fuego (3763 m) and the Agua (3766 m) which dominate the basin of Antigua and Guatemala, the Pacaya (2552 m). Despite the high seismicity, man has thickened on these basins and on the sides of these reliefs to an exceptional extent and this is due to the fertility of the volcanic, lava and tufaceous soils (tepetate), both for the high average altitude, which mitigates the tropical climate. The Pacific coastal selvedge is no more than 50 km wide and is formed by alluvial soils deposited by the rivers that descend from the volcanic cordillera, whose slope is never very harsh. As for the northern appendix of the country, the Petén, it is a flat region, made up, like all of the Yucatán, of limestone plateaus that overlap Cenozoic formations with Mesozoic substrates, all with widespread karst morphologies.
In relation to the general morphology, the rivers do not have very extensive basins; shorter and torrential are the streams that flow to the Pacific, more important and with a more regular regime those that descend to the Sea of the Antilles. The largest river is the Motagua, which collects the waters of a large section of the Caribbean side; Navigable for a good half of its course, it flows into the Gulf of Honduras, where a sandy bar closes its outlet forming the bay of Amatique (and here lies the largest port in Guatemala, Puerto Barrios). Rivers, such as La Pasión, also flow down from the northern side, which flow to the Gulf of Mexico through the Usumacinta.. In Petén the drainage of the waters is complicated by the structure of the region, which also has a karst, underground hydrography: in the center of it the Petén Itzá lake opens up. On the Pacific side the rivers, all short (Samalá, Madre Vieja, etc.), descend to the coast in a normal direction. Guatemala is famous for its many beautiful lakes; among those that occupy the depression basins of the volcanic highlands, the largest is the aforementioned Atitlán, but the largest lake in the country is the Izabal, between the Caribbean coast and the appendages of the Sierra de las Minas.