Geography

Geologic History and Formation

The isthmus now known as Central America took shape 60 million years ago (MYA); Nicaragua’s northern third is geologically the most ancient. In the area of Telpaneca and Quilalí [2], rocks dated at 200 million years old are thought to have once been part of a small Jurassic-Cretaceous continent that included the modern-day Yucatán Peninsula in Mexico [3] and the Antilles Islands.

To the south, what are now Costa Rica’s Talamanca Mountains formed an archipelago of isolated volcanoes. During the Tertiary period (65–1.7 MYA), intense volcanic activity and erosion produced large amounts of sediment and volcanic flows that accumulated underwater.

At least two periods of intense volcanic activity: one in the Eocenic-Oligocenic epoch (55–25 MYA) formed the lesser features of Nicaragua’s central highlands, and a second in the Miocene (25–13 MYA) produced the larger mountains in Matagalpa and Jinotega. Eleven million years later, shifting tectonic plates in the Pacific and Caribbean lifted the seabed, forming the Pacific region.

When the Cocos plate slid under the Caribbean plate, the main volcanic mountain range running northwest–southeast across the Pacific plains blistered to the surface. Ocean water from the Atlantic rushed in along a broad sunken valley of the Pacific plate now known as the Nicaraguan Depression, and pooled, forming the lakes. Some geologists believe the Atlantic and Pacific actually connected at this point in time and were later cut off by volcanic sedimentation. Erosion began pulling material from the landmass outward to the sea, building up Nicaragua’s Pacific region and gradually forming the Atlantic coast.

Plate tectonics theory, in spite of being widely accepted since the 1960s, is most frequently criticized for its failure to adequately explain the geology and geography of several regions of the world, including Central America. It is highly probable that our concept of the geological events that formed Central America will change as geologic science progresses. Regardless of the mechanism, however, convergence of the plates ensures crustal instability, which manifests itself in frequent volcanic and earthquake activity in all of Central America, and especially in Nicaragua.

Volcanoes and Mountain Ranges

Nicaragua [1] has about 40 volcanoes, a half dozen of which are usually active at any time, whether venting light, clouds of gas or actually erupting. Running parallel to the Pacific shore, Nicaragua’s volcanoes are a part of the Ring of Fire that encompasses most of the western coast of the Americas, the Aleutian Islands of Alaska, Japan, and Indonesia. The Maribio (Nahuatl for the “giant men”) and Dirian volcano ranges stretch nearly 300 kilometers from the Concepción and Maderas in the middle of Lake Nicaragua to Cosigüina, which juts into the Gulf of Fonseca.

The first volcanic event in recorded history was a major eruption of Volcán Masaya [4] in the early 1500s. The lava formed the present-day lagoon at the base of the mountain. Another great lava flow occurred in 1772, leaving a black, barren path still visible today where the Carretera Masaya highway crosses it. In 1609, Spanish settlers abandoned the city of León when Momotombo [5] erupted.

And in January of 1835, Volcán Cosigüina [6] violently blew its top, hurling ash as far away as Jamaica and Mexico, covering the area for 250 kilometers around the volcano in ash and burning pumice and forcing the entire peninsula into three days of darkness. All this volcanic activity is responsible for the exceptional fertility of Nicaragua’s soils, most notably the agricultural plains around Chinandega [7] and León [8].

Volcán Masaya is the most easily accessed of Nicaragua’s volcanoes and boasts a paved road leading right to the lip of the crater. Volcán Masaya is actually formed of three craters, the largest of which, Santiago, is the only crater in the Americas that contains a visible pool of incandescent liquid lava in its center. The visibility of this lava fluctuates on a 30-year cycle and was best seen 1965–1979.

Climbing a few Nicaraguan giants is a great way to experience Central America [9].

San Cristóbal is the highest peak, at 1,745 meters. A smaller peak adjacent to San Cristóbal, Volcán Casita still bears the immense scar of the landslide that buried thousands in an avalanche of rock and mud during Hurricane Mitch—and trembled briefly again in January of 2002. Isla de Ometepe’s twin cones are popular for hiking and easily accessible. No matter where you hike, always hire a guide, as several foreigners have gotten lost and perished while peak bagging.

Momotombo, San Cristóbal, and Telíca are the most active peaks and are prone to emit plumes of poisonous gases, smoke, and occasionally lava. La Isla de Ometepe [10]’s Volcán Concepción (1,610 meters) last blew its top in 2005 and 2007. The other half of Ometepe (Nahuatl for “two peaks”) is Volcán Maderas [11] (1,394 meters) which sleeps, its crater drowned in a deep lagoon that feeds a thriving jungle.

Volcán Telíca, just north of León [8], erupts approximately every five years, while gas vents at its base churn out boiling mud and sulfur. Neighboring Cerro Negro [12] is one of the youngest volcanoes on the planet: It protruded through a farmer’s field in the middle of the 1800s and has since grown in size, steadily and violently, to a height of 400 meters. Cerro Negro’s last three eruptions have been increasingly powerful, culminating in 1992 when it belched up a cloud of burning gases and ash seven kilometers high, burying León under 15 centimeters of ash and dust. Eight thousand inhabitants were evacuated as the weight of the ash caused several homes to collapse.

Volcán Momotombo [5]’s (Nahuatl for “great burning peak”) perfect conical peak is visible from great distances across the Pacific plains, as far away as Matagalpa. Momotombo is responsible for approximately 10 percent of Nicaragua’s electricity via a geothermal plant located at its base. It hasn’t erupted since 1905, but Momotombo remains a monster whose menace is taken quite seriously. In April 2000 it rumbled long enough to get Managua [13]’s attention, then quieted back down (for now).

A popular day trip from Granada [14] is the cloud forest park and coffee plantations of Volcán Mombacho [15] (1,345 meters), a dormant volcano whose explosion and self-destruction formed the archipelago of isletas in Lake Cocibolca. Mombacho took its modern shape in 1570 when a major avalanche on the south slope opened and exposed the crater, buried an indigenous village of 400 inhabitants in the process.

Three lesser mountain ranges dominate Nicaragua's center and north: the Cordilleras Isabelia, Huapi, and Chontaleña. These three ranges radiate northeast, east, and southeast, respectively, from the center of the country, gradually melting into the lowland jungle and swamps of the Atlantic coast. Their half-dozen prominent peaks were the scene of intense fighting during several conflicts in Nicaraguan history. Nicaragua’s highest point, Cerro Mogotón, at 2,107 meters, is located along the Honduran border in Nueva Segovia.

Lakes and Lagoons

Two lakes, Cocibolca (Lake Nicaragua) and Xolotlán (Lake Managua), dominate Nicaragua [1]’s geography, occupying together nearly 10 percent of the country’s surface area.

Lake Xolotlán, although broad (1,025 square kilometers), is shallow with an average depth of only seven meters. It reaches its deepest—26 meters—near the island of Momotombito [5]. Lake Managua is, for the most part, biologically dead, after a century of untreated human waste and extensive dumping of industrial wastes during the 1970s, including lead, cyanide, benzene, mercury, and arsenic.

The tremendous opportunities for tourism, recreation, and potable water for human consumption that a clean lake would facilitate have led to an ambitious plan to detoxify Xolotlán. Backed by loans from Japan and the World Bank, the project has already begun collecting and treating Managua’s sewage and, gradually, cleansing the lake itself in water treatment plants on the lakeshore. See the result for yourself on a booze cruise from Managua’s Malecón [16].

Lake Cocibolca is the larger of Nicaragua’s two lakes and one of Nicaragua’s greatest natural treasures. At 8,264 square kilometers and 160 kilometers long along its axis, Lake Cocibolca is nearly as big as the island of Puerto Rico and lies 31 meters above sea level. It’s also deep—up to 60 meters in some places, and relatively clean. The prevailing winds, which blow from the east across the farmlands of Chontales, make the eastern part of Cocibolca calm and the western half choppy and rough. A massive pipe system is presently being designed which, if built, will carry drinking water from Cocibolca to Managua to help meet the needs of the capital’s rapidly growing population.

Nearly a dozen stunning lagoons mark the maws of ancient volcanic craters. Around Managua [13] are the Nejapa, Tiscapa, and Asososca lagoons. West of Managua, the picturesque twin craters of Xiloá [17] and Apoyeque [17] form the Chiltepe peninsula. Near Masaya [18], the 200-meter-deep Laguna de Apoyo [19] was formed sometime in the Quaternary period (1.6 MYA) by what is thought to be the most violent volcanic event in Nicaragua’s prehistory. Not far away is Laguna de Masaya, at the base of the volcano of the same name. Other gorgeous lagoons flank Volcán Momotombo [5] in the craters of the Maderas [11] and Consigüina volcanoes [6].

Rivers

To the original Spanish settlers in Granada [14], the Río San Juan [20] was the elusive “drain” of Lake Cocibolca; since then, the possibility of traveling up the Río San Juan, across Lake Cocibolca, and then by land to the Pacific Ocean has made the San Juan the most historically important river in Nicaragua.

In the years of the gold rush, thousands of prospectors navigated up the Río San Juan en route to California; some made the return trip laden with riches, others with nothing. These days, several sets of rapids and decades of sedimentation reduce its navigability, exacerbated by shifts in the riverbed from occasional earthquakes. Cattle ranches and small farms primarily producing basic grains line both shores (farmers on the southern shore identify more closely with Costa Rica and even use its currency).

Formed by the confluence of three major rivers—the Siquia, Mico, and Rama—the Río Escondido is the principal link in the transportation corridor from Managua [13] to Bluefields and the Atlantic coast. Produce and merchandise (and busloads of travelers) reach El Rama and then proceed down the Escondido. The Escondido and its tributaries are important to the cattle industry in Chontales, but massive deforestation along its banks have unleashed dangerous floods that frequently put the river port of El Rama under water.

The 680-kilometer-long Río Coco is the longest river in Central America, fed by headwaters in both Nicaragua and Honduras. Also known as the Río Segovia or its indigenous name Wanki, the Coco traverses terrain that varies from several minor canyons to vast stretches of virgin forest. The indigenous Miskito people, for whom the river bears great spiritual significance, live in small communities along its shores.

The Estero Real [21] (Royal Estuary), at 137 kilometers in length, is the most consequential body of water on the Pacific coast and is one of Nicaragua’s best places to spot waterfowl. It drains most of northwestern Nicaragua through extensive mangroves and wetlands to the Gulf of Fonseca and is the nucleus of extensive shrimp-farming operations.

Soils

In the Pacific region, the volcanic soils are highly fertile and mineral-rich. The mountainous north and central regions of Nicaragua are less fertile basalt, andesite, and granite-based soils, and their steeper slopes are prone to erosion and soil degradation. The better soils are usually found alongside rivers where deforestation and fierce storms such as Hurricane Mitch (1998) haven’t carried it away, stripped it of its nutrient value, or buried it under thick layers of sand. In the north and northeast towards the Caribbean, the weak quartz-based soils can bear little more than thin stands of white pine.

The Sébaco Valley, thought to have once been the bed of an immense lake, has thick, black clay soils that impede the production of corn or beans but greatly facilitate wet rice farming.