This week we will head to the Republic of Panama! I’ve never visited, but I’ve enlisted the expert help of geologist Jacques LeBlanc, who will be our guide. Off we go!
Sharon Lyon
Editor, GeoLifestyle
The Reef Rock of Portobelo
Coral reef rock composing the walls of Fort Santiago de la Gloria, Portobelo; Courtesy of Jacques LeBlanc.
Visit the town of Portobelo on the Caribbean Sea to experience the historical and archeological sites of Fort San Jerónimo, Fort Santiago de la Gloria, and the Real Aduana de Portobelo (Royal Customs House of Portobelo). All three are part of the UNESCO World Heritage Site known as Fortifications on the Caribbean Side of Panama: Portobelo-San Lorenzo.
Historic places:
Both forts were constructed in the late 16th century to protect the Spanish colonial trade route, and both were attacked by pirates, including the infamous Henry Morgan. The forts were destroyed and rebuilt several times.
The Royal Customs House was constructed between 1630 and 1634 and used to inspect, tax, and store vast amounts of gold, silver, and other valuable goods which were transported from South America to Spain.
The building served as a local government office and school after Panama’s independence from Spain in 1882. Today, it houses the Museo de la Real Aduana de Portobelo (Museum of the Royal Customs House of Portobelo).
Coral reef construction:
Discoverers in the New World used coral reef rock, which was abundant and easier to cut than the igneous rock found inland, to construct their custom homes and buildings. Some walls were up to three meters thick.
Reef rock is naturally porous, helping it withstand the humid and salty environment. Its lighter weight made it easier to transport. Not all corals are suitable for building materials.
LeBlanc has analyzed the rocks and identified the two primary genera used in the historic buildings: Siderastrea (massive starlet coral) and Diplora (grooved brain coral).
Live coral rock from a nearby reef was used in 1997 to renovate St. Jeronimo Fort, aiming to maintain historical accuracy. However, this construction damaged the reef and upset environmentalists. Protections have now been put into place.
Outcrop of columnar andesite, Los Ladrillos, near Boquete; Courtesy of Jacques LeBlanc.
Our next stop is near the northern mountain town of Boquete. Los Ladrillos is a popular destination for rock climbers.
The geology of the site: Although an internet search will tell you the rock here is columnar basalt, LeBlanc tells me it is actually columnar andesite.
The columns were formed during eruptions of the Barú volcano, the highest mountain in Panama at 3,475 meters above sea level. They are relatively recent at just 180,000 years old.
Andesite, an intermediate fine-grained volcanic rock, formed from rapid cooling of the lava during its ascent to the surface. At Los Ladrillos, the rock is porphyritic, with abundant amounts of plagioclase phenocrysts, interstitial volcanic glass and disseminated magnetite.
Other highlights to see:
Nearby hikes include the Pipeline Trail and the Lost Waterfalls Trail (Las Tres Cascadas) with its suspension bridge.
Near the border of Costa Rica, visit Volcán Barú National Parkand be on the lookout for colorful birds, including quetzals and toucans.
Black sand beach, Nueva Gorgona; Courtesy of Jacques LeBlanc.
From December to May, tourists flock to the town of Nueva Gorgona on the Pacific Ocean to enjoy the pleasant temperatures and wide black sand beaches.
The black sands of Nueva Gorgona Beach formed from the erosion of basalt and andesitic to rhyolitic tuffs from the Cerro Chame Dome and El Valle Volcano. The sediment is deposited on the beach by the Chame River and a creek in the area.
Waves and tidal activity distribute the sand along the length of the beach, where it mixes with siliciclastic sand.
The sands have a high percentage (up to 90 percent) of magnetite, and rich concentrations of heavy minerals.
Enjoy walking along the beach but be aware that the difference between high and low tides of over 6 meters. At high tide, some areas are blocked by structures or rock mounds.
Learn more about the geology of the black sands here.
The Panama Canal
Photo Caption: What is in the image, who to credit
Many tourists view Panama from a cruise ship passing through the Panama Canal. The canal is a technological marvel which changed global shipping patterns, removing the need for ships to navigate the Drake Passage to pass from ocean to ocean.
Panama Canal history:
A French entrepreneur led the initial attempt to build a sea-level canal across the Panama Isthmus from 1880–1889.
Concessions were given to the Colombian government who possessed the isthmus.
Difficulties with the rugged terrain and heavy personnel losses from tropical diseases forced the French canal company to collapse.
In 1904, the United States purchased the French equipment and excavations, as well as the Panama Railroad, and construction commenced.
Although the canal was built under three U.S. presidents—Theodore Roosevelt, William Howard Taft, and Woodrow Wilson—Roosevelt made most of the critical decisions.
He chose the route through Panama rather than Nicaragua, supported Panama’s secession from Colombia, and chose a lock-and-lake design over a sea-level canal.
One of the greatest barriers to the canal was the continental divide. In 1913, Woodrow Wilson’s telegraph signal triggered an explosion that flooded the Culebra Cut across the divide, joining the Atlantic and Pacific Oceans.
In 1977, President Jimmy Carter ignited the 20-year process of transferring control of the canal to Panama. The canal is now administered by the Panama Canal Authority.
The Panama Canal Expansion Project, from 2007–2014, widened and deepened the canal and added an extra set of locks to accommodate larger ships.
Visitors to the canal can watch as the massive cargo ships carrying tons of shipping containers pass through.
In a few weeks, I’ll be going to Arizona for the Tucson Gem and Mineral Show—the largest gem and mineral show worldwide! If you’ve attended and have ideas on what I should be sure not to miss, please let me know!
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