Friday, January 31, 2014

Masaya Volcano and Grenada City, Nicaragua

Our last stop on this African and South American adventure was at the active volcano of Masaya and the colonial city of Grenada on the shores of Lake Nicaragua.

On the rim of the crater. The steam and gaseous smoke hug the inner walls.

Hiking up to the sister crater to the east

Looking back to Masaya 

This crater has been inactive for many years and we could see its floor. The steam and vapor in the other cone precluded a view inside.

Note the alternating cliffs and thin slopes. The cliffs are formed from lava flows while the slopes are horizons of ash and cinders that are unconsolidated, thus weathering into vegetation-covered slopes.

Every now and then the wind would shift and we could see a bit into Masaya crater

The unvegetated ridge in the background is part of the outer ring of a caldera and the lack of trees is due to the volcanic gases that blow in that direction. It was a fantastic morning.

Masaya last erupted in 2008

Note the lava flow that spilled from over the rim of the crater in 1772

We drove east to visit the colonial city of Grenada 

Fantastic architecture

Colorful street scenes

Archaeological finds from near Grenada

 I love colonial porches

Back in Managua we visited the ruins of the city cathedral, destroyed by the 1972 earthquake

And we got to visit the wonderfully preserved footprints made about 2,120 BP, in soft volcanic soil. The site is called Ancahualinca. A description can be read here:

The trackway is remarkably preserved in stone now

They are protected by a ramada that shed rain

And are found within a neighborhood in Managua. Thanks for reading. I'll be back home with Helen on Saturday.

Thursday, January 30, 2014

Great Day Flying From Iguazu Falls to Nicaragua

We took an eight hour flight from South America to Central America. Our route was over the ParanĂ¡ River, the Amazon basin, and into the southern part of Nicaragua. I gave my fifth lecture when we flew over the Andes in northern Ecuador. It was cloudy so I didn't miss anything. I got some great shots of rivers and volcanoes on the way in.

Our hotel at Iguazu, the Das Cataratas

Summertime clouds over southern Brazil and Paraguay 

This is likely the Parana River and the boundary between Brazil and Paraguay 

As we approached the Amazon River, we saw many looping tributaries

There were many oxbow lakes, places where a loop in the River had been cut off. The course of this river is similar to the San Juan in Utah, except this one is not incised 1,200 feet.

As we landed in Iquitos, Peru for fuel, the great Amazon came into view. A boat on the river would barely be discernible, the river is that large.

More great clouds

And then Lake Nicaragua came into view with a volcanic island shrouded in clouds within it

This the famous two-volcano island of Ometepe. This conical gem is called Vulcan Concepcion. There is a cloud on top of the cone making it only look like it is erupting.

Aerial view of the colonial city of Grenada on the shores of Lake Nicaragua. I will have pictures of the colorful houses from here in my next post.

Grenada is framed by the Mombacho volcano, which lost it's top in a fiery eruption some 20,000 years ago

There are many "lagoons" in this area of Central America and they are water-filled calderas. This one is the Apayo Lagoon just west of Grenada.

And then the smoking Masaya volcano came into view. We did a hike between the two craters and I will post pictures of the hike soon!

Iguazu Falls, Brazil

It was a short flight from Buenos Aires to Iguazu and this would be our only one night stay. But we packed a lot into the short time we were here.

Flying into the Brazilian side of the falls 

Into the jungle for a boat ride on the Iguazu River.

The falls pour over Cretaceous-age basalt, erupted about 121 Ma and known as the Parana volcanics. These lavas are related to the rifting that occurred when the South Atlantic Ocean opened between Africa and South America. The polygons here are weathering features as water invades the fractures and begins to chemically dissolve the rock along these lines of weakness.

Our craft as we head up the rive towards the falls

The power of the falls is astounding and flow levels were high enough that we dare not travel father up to the main falls

It was a wet and enjoyable ride

Time to view the falls from the top

Looking into the Devil's Throat on the Brazilian side. This was one of the highest levels of flow I have ever seen here and record flows were recorded last June. The power and sound of the falls is impressive.

The average discharge of the Iguazu River is between 600,000 and 1,500,000 cubic feet per second!

It was hot and steamy during our visit, about 92 degrees with about 95% humidity. I was soaked.

Iguazu Falls

These is a catwalk constructed right above the lip of the falls. This photo looks downstream over the lip. In June the water ran over this catwalk.

At the end of the catwalk looking upstream

Sunset at the falls

At the end of the trail where the Devil's Throat is located. The falls are an impressive knickpoint on the River that is slowly migrating upstream. As rocks are plucked off the edge of the falls, the falls gradually retreat in the upstream direction.

The Itaipu Dam on the Parana River is one of the largest hydroelectric plants in the world. Only the Three Gorges Dam is larger. When this dam was completed in the 1980's, it drowned out the Seven Falls on the Parana, the location of a knickpoint on that river. My next post will be about the fantastic flight from Brazil to Nicaragua.

Tuesday, January 28, 2014

Buenos Aires, Argentina

I am aware the geology has been "light" in these postings but we are going to Iguazu Falls this afternoon and then to the Central American volcano's after that. There will be more geology then. For now, enjoy these photo's from one of my favorite cities, Buenos Aires, Argentina.

This is a shot from 37,000 feet down to the Valdez Peninsula, along Argentina's east coast. There is much wildlife here including the Southern Right Whale and many seals. I traveled overland on this peninsula in the 1990's.

These are the famous Argentinian Pampas, a large area of flat land well positioned latitudinaly for agriculture (read, cattle raising and beef)

The image of Eva Peron is everywhere in Buenos Aires. She is both revered and despised, depending on what part of the economy you belong to. She was a champion of those who otherwise had no voice in government or society. On this trip, I have been struck by how often this theme comes up everywhere we go. It is a story of the "haves" and the "have nots".

A view of the cathedral in Buenos Aires

This of course is where Pope Francis served before going to the Vatican

On the Plaza de Mayo in central Buenos Aires

One of the European cities in South America

La Boca is a lively and colorful district here

More La Boca

Mural of the tango

Hats for sale in the flea market, called the American market here

We went to an estancia and we're give a show by the gauchos

Riders race about the length of a football field with silver pins and attempt to pierce a small ring

My camera captured the only successful attempt by the most experienced gaucho