Cleaning up the Juanacatlan Falls, the “Niagara of Mexico”

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Jan 142016
 

Geo-Mexico has repeatedly lamented the sad state of the Juanacatlán Falls, the “Niagara of Mexico”, near Guadalajara. More than a century ago, they were considered a national treasure. Indeed, in 1899, they were among the earliest landscapes to be featured on Mexican postage stamps.

In 2012, we reported that Greenpeace demands action to clean up Mexico’s surface waters. Greenpeace activists chose to protest at the Juanacatlán Falls to call attention to the poor quality of Mexico’s rivers and lakes. The activists cited government statistics showing that 70% of Mexico’s surface water was contaminated, mostly from toxic industrial dumping, rather than municipal sewage.

Greenpeace activists at El Salto de Juanacatlán, 22 March 2012. Photo: Greenpeace.

Greenpeace activists at El Salto de Juanacatlán, 22 March 2012. Photo: Greenpeace.

Last year, we returned to the theme and looked at how the Juanacatlán Falls had been transformed from the “Niagara of Mexico” to the “Silent River”.

Our concluding paragraph on that occasion bears repeating:

Is it too much to hope that the government, corporations and society in the El Salto area can all come together to remedy this appalling tale of willful mismanagement? Local residents are right to insist on the enforcement of existing water quality regulations and on the implementation of remedial measures to reverse the decline of this major river and its once-famous waterfalls. Even more importantly, urgent measures are needed to reverse the deteriorating public health situation faced by all those living or working nearby.

Finally, some good news. Author and activist John Pint, who has done far more than most to publicize the scenic wonders of Western Mexico (including dozens of places that fall way outside the usual tourist guides) reports that the inflow from the 66-km-long Ahogado River, one of the rivers that feeds into the Santiago River just before the Juanacatlán Falls is being cleaned up, with a dramatic, positive impact on the beauty of the Falls themselves. According to Pint’s first-hand report and photographs – Is Guadalajara’s most infamous waterfall now clean? – the smelly, toxic foam that has marred the Falls for decades has become a thing of the past. While this does not mean the water is completely clean, it is certainly an encouraging start.

The Ahogado River itself continues to receive pollutants, and its water remains heavily contaminated, but a  300-million-peso treatment plant, which apparently began operations in 2012, is removing some of the worse contaminants prior to the river joining the Santiago River. There is still a lot of work to be done here if the Juanacatlán Falls are going to be restored to their former pristine beauty, but Geo-Mexico is delighted to hear that progress is (finally) being made.

What a shame that it took the death of eight-year-old Miguel Ángel López in 2008, and years of adverse effects on the health of local inhabitants, before federal and state authorities took decisive action. Later this year, Geo-Mexico hopes to revisit the Falls for the first time in twenty years to see just how much they’ve improved. Watch this space!

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Ecocide in Lake Cajititlan, Jalisco: massive fish death

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Sep 062014
 

Hundreds of thousands of dead fish have washed up on the shores of Lake Cajititlán in Jalisco in the past ten days.

Lake Cajititlán is about 9 kilometers (5.6 miles) long and 2 km wide. It is mid-way between the city of Guadalajara and Lake Chapala, Mexico’s largest natural lake. Fortunately, Lake Cajititlán does not have an outlet, so water and fish from the lake can not enter other nearby streams or lakes.

Map of Lake Chapala, Jalisco, Mexico

Map of Lake Chapala, Jalisco, Mexico. Credit: Tony Burton; all rights reserved.

According to government officials, about 3 million dead popoche chub (Algansea popoche) with a combined weight of 82 metric tons were removed from Lake Cajititlán in the latest ecocide.

Initial reports contained conflicting versions of events, with local fishermen claiming far higher losses than government officials. The currently accepted figure of 82 metric tons suggests that the fishermen’s estimate was far closer to reality than the early “official” figures.

cajititlan-ecocide

(AFP Photo / Hector Guerrero)

Local authorities at first tried to persuade residents that the die-off was part of a “natural cycle”. However, this idea was quickly dispelled by state and federal agencies who are continuing investigations to establish the precise causes of the ecocide. Their preliminary technical studies have confirmed that the die-off of fish was due to contaminated water with dissolved oxygen levels well below the limits for a healthy fish population. The contamination appears to originate from raw sewage entering the lake and the inefficient operation of the existing sewage treatment plants.

Low oxygen levels could also result from seasonal rainy season runoff washing excess fertilizers into the lake, increasing the water’s nitrogen and phosphorus loads, promoting eutrophication.

State authorities have issued an environmental emergency alert for the lake, but have consistently maintained that the event has not endangered the health of local residents.

This is the fourth fish kill affecting Lake Cajititlán in 2014. This latest ecocide is only one of several ecological disasters that have befallen Mexico in recent weeks.

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Recent progress in waste water treatment in Mexico

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Aug 252014
 

Two wastewater treatment plants have been in the news recently. The first is the $230 million Agua Prieta wastewater treatment plant, located north of Guadalajara in Jalisco, which was formally inaugurated last month. It is the first stage in a plan to restore the heavily polluted Santiago River back to health. The Santiago is the outflow from Lake Chapala and receives pollutants from the industrial zone of El Salto outside Guadalajara. The initial capacity of the Agua Prieta plant is 6,500 liters/second, almost all of which is returned to the river after treatment.

The plant was built by a consortium led by ICA subsidiary Conoisa, Atlatec, and Servicios de Agua Trident under a 20-year concession. President Enrique Peña Nieto claims on his government webpage that, “Integrated, sustainable water management is a government priority. The challenge is even greater because almost 50% of the wastewater returned to the environment does not undergo any form of treatment… The Agua Prieta Wastewater Treatment Plant in Zapopan… [will] improve the quality of life of 3.3 million inhabitants in the metropolitan area of Guadalajara… It will treat 82% of the wastewater in the area, and 100% when the complementary sewage works are completed.”

agua-prieta-wastewater-According to government figures, waste water treatment coverage at the national level is currently 50.3%, with a 2018 target of 63%. Agua Prieta has raised national coverage to 53.3%, and will boost it to 54.3% once the plant is operating at full capacity and treating 8,500 liters/second of wastewater. At the state level, Jalisco is now treating 32% of its wastewater.

The Agua Prieta plant is currently the largest of its kind in Mexico and is powered by biogas derived from the wastewater sludge. However, an even larger plant is under construction, in the state of Hidalgo in central Mexico. The Atotonilco Wastewater Treatment Plant is being built by a consortium, including Mexican construction companies ICA and IDEAL, Mitsui subsidiary Atlatec and Spanish firm Acciona Agua, that won the concession to design, build, and operate this plant for 22 years, at which point the plant will be transferred to federal ownership. Work began in 2010 and is due to be completed by 2015.

The Atotonilco Wastewater Treatment Plant will be the largest wastewater plant in Latin America and one of the largest in the world, with a biological treatment capacity of 23,000 liters/second (1.99 million m3/day). The wastewater treatment is performed by a series of conventional processes, with an additional chemical process during the rainy season. Treated waters from this plant are already being used in agriculture without any additional cleaning steps. The plant is self-sufficient in terms of energy usage, since it converts the methane offgas from the wastewater sludge into electrical energy.

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Monitoring air pollution in Guadalajara

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Jun 162014
 

Air pollution in the city of Guadalajara, the state capital of Jalisco, has worsened over the past decade, though there are some recent signs of improvement :

The Jalisco Environmental Agency now has a webpage where residents and travelers alike can now monitor Guadalajara’s air quality on an hourly basis. Readings for 10 stations are superimposed on a basemap on that page, together with links to graphs showing recent trends and other meteorological data. Tabs above the map also give a link to the current wind conditions across the city. Historical data (in Spanish) can also be accessed via the link to “Datos”.

Screenshot of Guadalajara air monitoring webpage

Screenshot of Guadalajara air monitoring webpage. Note: Two stations are shown as undergoing maintenance.

The map provides summary data in IMECAs, which stands for Índice Metropolitano de la Calidad del Aire (Metropolitan Index of Air Quality). IMECAs are a compound index combining measurements of concentrations of ozone (O3), sulphur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO) and particles smaller than 10 micrometers (PM10).

In Guadalajara, formal smog alerts are issued if average readings rise above 150 IMECAs (“Very Bad”) for more than two consecutive hours. If readings rise above 200 IMECAs (“Extremely Bad”), then “serious alerts” impose restrictions on vehicle use and may lead to the suspension of school classes.

In Guadalajara, the worst air quality tends to be in the southern and eastern sections of the city. It also tends to occur in the months of April and May, immediately before the rainy season gets underway. The webpage system gives everyone an easy way to check these assertions!

In Guadalajara, mitigation efforts are centered mainly on reducing vehicle emissions (partly by stricter emissions testing and verification, and partly by improvements to the public transport network) since they are the main source of pollution. To date, there are no plans in Guadalajara to introduce a “Day without car” program similar to that in Mexico City:

Teaching idea

Use the Jalisco Environment Agency webpage to monitor Guadalajara’s air pollution and identify any patterns or trends related to air pollution in the city. Consider suggesting one or more hypotheses, such as “Air pollution gets worse in the afternoon”, or “The level of air pollution in eastern Guadalajara is worse than in western Guadalajara”, before testing your ideas using the online data.

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Retirees and “residential tourism”: a case study of Chapala-Ajijic in Jalisco

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Jan 162014
 

Retirees, mainly from the USA and Canada, form a special subgroup of tourists. About 1 million US visitors to Mexico each year are over the age of 60. Their total expenditure is about $500 million a year. Three-quarters arrive by air; half of these stay 4-8 days and almost one in ten stays 30 days or longer. Half stay in hotels, and one-third in time-shares; the remainder either stay with family or friends, or own their own second home. Of the 25% arriving by land, almost one in three stays 30 days or more. For Canadians, the patterns are broadly similar except that a higher percentage arrive by air.

The number of retiree tourists is relatively easy to quantify. However, it is extremely difficult to place accurate figures on the number of non-working, non-Mexicans who have chosen to relocate full-time to Mexico. Technically, these “residential tourists” are not really tourists at all but longer-term migrants holding residency visas. They form a very distinct group in several Mexican towns and cities, with lifestyle needs and spending patterns that are very different from those of tourists. Their additional economic impact is believed to exceed $500 million a year.

Map of Lake Chapala, Jalisco, Mexico

Map of Lake Chapala, Jalisco, Mexico. Credit: Tony Burton; all rights reserved.

The largest single US retirement community outside the USA is the Guadalajara-Chapala region in Jalisco, according to state officials (see map). The metropolitan area of Guadalajara, Mexico’s second city, has a population of about 4 million. The villages of Chapala and Ajijic (combined population about 40,000) sit on the north shore of Lake Chapala some 50 km (30 mi) to the south. Historically, Chapala was the first lakeshore settlement to attract foreign settlers, as early as the start of the 20th century. Today the area is home to a mix of foreign artists, intellectuals, escapees (of various non-judicial kinds), pensioners and ex-servicemen. In the last 40 years, Ajijic has become the focal point of the sizable non-Mexican community living on the lakeshore. Depending on how they are defined, there are probably between 6000 and 10,000 foreign residents in the Chapala-Ajijic area, the higher number reflecting the peak winter season. About 60% of retirees in the area own their own homes or condos, though many still own property in the USA or Canada as well, and many make regular trips north of the border.

The main pull factors for residential tourists are an amenable climate; reasonable property prices; access to stores, restaurants and high quality medical service; an attractive natural environment; a diversity of social activities; proximity to airports; tax advantages, and relatively inexpensive living costs.

David Truly has suggested that conventional tourist typologies do not work well with Ajijic retirees. He identified migrant clusters with similar likes and dislikes. Retirees vary in education, travel experience and how they make decisions about relocation. Early migrants tended to dislike the USA and Canada and adapted to life in Mexico. They were generally content with anonymity unlike many more recent migrants. Traditional migrants appreciate all three countries, but have chosen Mexico as their place of permanent residence. Many new migrants do not especially like the USA or Canada but are not particularly interested in Mexico either. They seek familiar pastimes and social settings and are content to have relatively little interaction with Mexicans.

The large influx of residential tourists into small lakeside communities like Ajijic inevitably generates a range of reactions among the local populace. From empirical studies of regular tourism elsewhere, George Doxey developed an “irritation index” describing how the attitudes of host communities change as tourist numbers increase. His model applies equally well to residential tourists. In the initial stage the host community experiences euphoria (all visitors are welcome, no special planning occurs). As numbers increase, host attitudes change to apathy (visitors are taken for granted) and then annoyance (misgivings about tourism are expressed, carrying capacities are exceeded, additional infrastructure is planned). If numbers continue to grow, hosts may reach the stage of antagonism, where irritations are openly expressed and incomers are perceived as the cause of significant problems.

Residential tourism in the Chapala-Ajijic area has certainly wrought great changes on the landscape. Residential tourists have created a distinct cultural landscape in terms of architectural styles, street architecture and the functions of settlements. (Browse the Chapala Multiple Listing Service New Properties). Gated communities have been tacked on to the original villages. Subdivisions, two around golf courses, have sprawled up the hillsides. Swimming pools are common. Much of the signage is in English. Even the central plazas have been remodeled to reflect foreign tastes. Traditional village homes have been gentrified, some in an alien “New Mexico” style.

On the plus side, many retirees, as a substitute for the family they left behind, engage in philanthropic activities, with a particular focus on children and the elderly. Retiree expenditures also boost the local economy. Areas benefiting from retirees include medical, legal and personal services, real estate, supermarkets, restaurants, gardening and housecleaning. Employment is boosted, both directly and indirectly, which improves average local living standards.

On the minus side, decades of land speculation have had a dramatic impact on local society. Land and property prices have risen dramatically. Many local people have become landless domestic servants, gardeners and shop-keepers with a sense that the area is no longer theirs. Crime levels have risen and some local traditions have suffered. The abuse of water supplies has resulted in declining well levels. Over zealous applications of fertilizers and pesticides have contaminated local water sources.

Other locations besides Chapala-Ajijic where a similar influence of non-Mexican retirees on the landscape can be observed include San Miguel de Allende (Guanajuato), Cuernavaca (Morelos), Mazatlán (Sinaloa), Puerto Peñasco (Sonara), Rosarito (Baja California) and Todos Santos (Baja California Sur). The most preferred locations are all on the Pacific coast side of Mexico.

As more baby-boomers reach retirement age, residential tourism offers many Mexican towns and cities a way of overcoming the seasonality of conventional tourism. Lesser-developed regions have an opportunity to cash in on their cultural and natural heritage and improve their basic infrastructure.

This is a lightly edited excerpt from chapter 19 of Geo-Mexico: the geography and dynamics of modern Mexico.

References:

  • Boehm S., B. 2001 El Lago de Chapala: su Ribera Norte. Un ensayo de lectura del paisaje cultural. 2001. Relaciones 85, Invierno, 2001. Vol XXII: 58-83.
  • Burton, T. 2008 Lake Chapala Through the Ages, an Anthology of Travellers’ Tales. Canada: Sombrero Books.
  • Doxey G.V. 1975 A causation theory of visitor‑resident irritants: methodology and research inferences. Proceedings of the Travel Research Association, San Diego, California, USA: 195‑8.
  • Stokes, E.M. 1981 La Colonia Extranero: An American retirement Community in Ajijic, Mexico. PhD dissertation, University of New York, Stony Brook, cited in Truly, D. 2002.
  • Truly, D. 2002 International Retirement migration and tourism along the Lake Chapala Riviera: developing a matrix of retirement migration behavior. Tourism Geographies. Vol 4 # 3, 2002: 261-281.
  • Truly, D. 2006 The Lake Chapala Riviera: The evolution of a not so American foreign community, in Bloom, N.D. (ed) 2006 Adventures into Mexico: American Tourism beyond the Border. Rowman & Littlefield: 167-190

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Aug 052013
 

A recent study published by the Clean Air Institute analyzed air pollution in 22 Latin American cities:

Six Mexican cities were included in the study: Mexico City, Guadalajara, Monterrey, Puebla, Ciudad Juárez and León. However, only limited data were available for Puebla, Cd. Juárez and León. One of the main conclusions of the study is that Mexico has about the worst urban air pollution in Latin America. It is believed to be responsible for about 15,000 deaths in Mexico each year.

The focus was on the following air pollutants:

  1. Particulate matter is divided into two measures; particles less 2.5 microns in diameter (PM2.5) and those less than 10 microns (PM10). PM2.5 pollution is extremely harmful because it penetrates deep into lungs causing inflammation and worsening heart and lung diseases. This can be fatal.
  2. Ozone is formed in the air when oxides of nitrogen and volatile organic compounds mix with intense sunlight. The very intense sunlight in Mexican cities makes them particularly prone to ozone pollution.
  3. Nitrogen dioxide (NO2) is caused by high temperature combustion of fossil fuels in vehicles, factories and power plants. It can aggravate lung diseases as well as contribute to ozone and fine particle pollution.
  4. Sulfur dioxide (SO2), which also comes from burning fossil fuels, contributes to heart and respiratory disease. Unfortunately, not all of the 22 cities had data on all four pollutants. Consequently comparisons among cities are a bit limited.

According to the study, Mexican cities had some of the worst urban particulate pollution in Latin America, significantly above WHO standards. Of the 16 cities with data, Monterrey had by far the worst PM10 pollution with 85.9 micrograms per cubic meter (ug/m3); considerably worse than the perennially dusty Lima with 62.2 ug/m3. Guadalajara came second with 70.1 ug/m3, Mexico City was 6th with 57.0 ug/m3, and León placed 11th with 39.0 ug/m3, even worse than Sao Paulo at 36.5 ug/m3. Though not in the study, Mexicali has worse PM10 pollution than Monterrey. Also Monterrey’s PM10 levels are much better than many major world cities including Cairo, Delhi, Kolkata, Beijing, Chengdu, Bangalore, Shanghai, Dacca, Jakarta, and Karachi.

Mexico City air quality in 1980 (Photo: Tony Burton)

Mexico City air quality in 1980 (Photo: Tony Burton)

Mexico did a bit better with respect to the more serious PM2.5. Of the 11 cities with data, Bogota was worst with 35.1 ug/m3 followed by Lima at 31.5ug/m3 and San Salvador and Montevideo at 28.0 ug/m3. The two Mexican cities with data, Mexico City (26.2 ug/m3) and Monterrey (25.9 ug/m3) were 6th and 8th.

Mexican cities also have some of the highest levels of ozone pollution. Of the ten cities with data, five of the six worst were Mexican cities. Guadalajara had the highest ozone pollution with 69.3 25.9 ug/m3 followed closely by León 68.9 at ug/m3. Mexico City was 4th (59.4 ug/m3); Monterrey was 5th (55.2 ug/m3); and Cd. Juárez came 6th (46.3 ug/m3), just ahead of Quito (44.1). Much better ozone levels were recorded by Sao Paulo (36.0 ug/m3), Santiago (28.8 ug/m3) and Bogota (21.1 ug/m3).

Cities in Mexico also had high levels of nitrogen dioxide. The highest levels were in Montevideo (70.0 ug/m3), but Guadalajara (57.2ug/m3), Mexico City (54.2 ug/m3) and León (45.5 ug/m3) placed 2nd, 3rd and 4th worst among the 14 cities with data. Monterrey was much better with the third lowest nitrogen oxide level (29.0 ug/m3), trailing only Lima (12.8 ug/m3) and Quito (23.3 ug/m3).

Mexican cities were also among the worst in terms of sulfur dioxide pollution. Of the 13 cities with data, León had by far the highest level with (23.4 ug/m3), followed by Medellin (16.0 ug/m3). Mexico City was 3rd worst (15.3 ug/m3); Monterrey was 4th (13.1 ug/m3); and Guadalajara was 6th (8.6 ug/m3).

In summary, the study indicates that Mexico has about the worst urban air pollution in Latin America. Fortunately, Mexico City, which used to be considered one of the most polluted cities in the world, has significantly improved its air quality in the last few decades. (see Rhoda and Burton, Geo-Mexico: The geography and dynamics of modern Mexico, p 177)

On the other hand, other major cities in Mexico have not had the same experience. The data in this study appear to suggest that among Mexico’s three biggest cities, Guadalajara has the worst air pollution followed by Mexico City and then Monterrey. (This study found insufficient data for comparisons with Puebla, Cd. Juárez and León.)

Other posts on urban air pollution:

Watch La Primavera’s geological history unfold via a short video animation

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Jun 292013
 

Only days after we published our third post about the Primavera Forest, near Guadalajara, we were alerted to an excellent 9 minute video animation of how the area was formed. This short video about “The Exciting Geology of Bosque La Primavera” was produced by geologist Barbara Dye during her stint as a Peace Corps volunteer in Mexico.

The video can also be viewed in Spanish:

Dye has also written a beautifully-illustrated 72-page guide (in Spanish) to the geology of the Primavera Forest, entitled “La Apasionante Geología del Área de Protección de Flora y Fauna La Primavera.

Previous posts about La Primavera:

What are the 10 main pressures threatening the Primavera Forest in Jalisco?

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Jun 222013
 

A 1988 Management plan for the Primavera Forest (Plan de Manejo Bosque La Primavera), published by the University of Guadalajara, included a detailed list of the then-existing pressures on the forest.

Sadly, not much has changed since then, and almost all the sources of pressure mentioned in that study still apply today.

The Primavera Forest. Credit: Semarnat, 2003

The Primavera Forest. Credit: Semarnat, 2003

The management plan argues that the key areas (see map) where careful management is essential include:

  • Cerro San Miguel and Cerro Las Planillas, the highest elevations in the area
  • The environs of the tourist spa of Río Caliente (this spa is now closed)
  • Mesa de Nejahuete, in the center of the volcanic caldera, and
  • Mesa del León, considered an important habitat, primarily for fauna

The plan identifies the following sources of concern (note that this list is in no particular order, and certainly not in order of highest pressure to lowest):

1. Tourism. Poorly planned recreation areas, such as autodromes and spas. Issues resulting from this source of concern include pollution, waste disposal, soil erosion, landscape degradation, habitat change, reduced fauna and, switching to a human focus, delinquency. Motorcycles and trail bikes are a particular problem because of the associated noise pollution, annoyance and risk to other visitors, habitat destruction, the displacement of fauna and often lead to accelerated soil erosion.

2. Ejidos. Any expansion of neighboring ejidos means more homes, deforestation and landscape alteration.

3. Quarrying. The quarrying of local rocks such as pumice or river deposits, as well as a number of abandoned quarries can result in habitat destruction, erosion, forest degradation, accelerated mass movements (landslides, rockfalls), posing a risk to infrastructure, access routes and the potential pollution of ground water.

4. Hunting. Hunters leave spent cartridges that can pollute the soil, as well as wounded and abandoned animals. Larger fauna have become progressively more scarce. In addition, the presence of individuals carrying firearms poses a security threat.

5. Cultivation and Overgrazing. Increased cultivation (primarily for sugar cane, corn and beans) has gradually nibbled away at the edges of the forest, with the clearance method of slash and burn being a particular problem since it greatly raises the risk of wildfires, soil degradation and deforestation. As the number of access routes increases, it is easier for local farmers to graze livestock in the forest, reducing the health of the  grassland, and leading to a relative abundance of unwanted plants and weeds, accelerated soil erosion and the possible contamination of water sources.

6. Deforestation. Deforestation is also a pressure on the forest, in which the cutting of woodland for fuel (including bonfires) and for firebreaks, leads to changes in habitat and soil use, with the secondary effects of increased erosion, reduced ground water recharge and varying degrees of secondary forest succession.

7. Geothermal Power. The potential development of some areas for geothermal power by the Federal Electricity Commission (CFE) has already involved the opening of access routes and would lead to noise contamination (with adverse effects on fauna) and possible pollution of ground water, air and soil, as well as deforested hillsides. The loss of vegetation cover would trigger accelerated erosion, and habitat destruction, further reducing water quality. Access routes attract other “users” such as those seeking to quarry local rocks or clear land for farming.

8. Settlements. Settlements and subdivisions have also encroached on the forest. Some are irregular/illegal settlements, but others are private homes and clubs. Regardless of economic level, these settlements result in a decrease in vegetation and the elimination of the soil’s litter layer, leading to soil compaction, lowered infiltration rates, and nutrient-depleted soils, as well as increased pollution and the gradual elimination of native fauna

9 Wildfires. Wildfires, such as that in 2012, destroy vegetation and cause a general degradation of the woodland. They can result in the accelerated degradation of soil, water and vegetation, leading to significant changes to soil structure, as well as increased runoff and reduced groundwater recharge.

10. Inadequate regulations. The problems faced by the Primavera Forest are compounded because the relevant local authorities have shown little interest in ensuring adequate regulations, supervision and enforcement.

Many of these ten major pressures are closely interrelated. Despite the good intentions back in 1988, it is clear now, with the benefit of hindsight, that the 1988 management plan did not achieve very much. Hopefully, in the not too distant future, and as the Primavera Forest gains international status as a possible Geo-Park, a more comprehensive and effective management plan can be devised and implemented.

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How was the Primavera Forest caldera in Jalisco formed?

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Jun 102013
 

In a previous post, we described the considerable geotourism potential of the Primavera Forest near Guadalajara:

In this post, we take a closer look at how this unusual area was formed.

Stages 1 and 2 (see diagram):

140,000 BP. The magma chamber beneath the surface began to fill with magma (molten rock underground) and grow in size.

By about 120,000 BP, several lava flows and domes had formed, made primarily of rhyolite, a silica-rich (“acid”) igneous rock. After each eruption, the magma level underground would subside for a period of time before pressure built up again towards the next eruption.

Formation of a caldera

Fig. 4 of Bullard (1962) “Volcanoes in history, in theory, in eruption”. Based on van Bemmelen (1929) and Williams (1941)

Stages 3 and 4

So much pressure had built up by about 95,000 BP that there was a huge explosion, sending 20 cubic kilometers (4.8 cubic miles) of rock and ashes high into the sky. The explosion covered 700 square kilometers (270 square miles) with volcanic materials, known today as the Tala tuff (tuff is the geological term for consolidated ash). This massive explosion caused the upper part of the magma chamber to collapse, leaving a caldera that was 11 kilometers (6.8 miles) wide. The Tala tuff includes large quantities of pumice, a light and porous volcanic rock formed when a gas-rich froth of glassy lava solidifies rapidly.

This caldera filled with water, creating a lake.

Stage 5

This stage began shortly afterwards when a series of ring domes were erupted around the edge of the caldera as the magma deep below the surface started to push upwards again, eventually forming small islands in the lake. These eruptions formed more pumice, blocks of which would break off and start to float across the lake as they gradually sank to the lake floor.

A further series of eruptions in about 75,000 BP led to a second series of ring domes. A combination of tectonic uplift and sedimentation had filled the lake in by about this time.

More volcanic domes have been created at approximately 30,000 year intervals since, in about 60,000 BP and about 30,000 BP; these domes were almost all on the southern and eastern margins of the caldera, and include the lava domes of El Colli and El Tajo on the outskirts of Guadalajara.

Many geologists appear quietly confident that lava and ash eruptions in La Primavera are a thing of the past. They consider that the Primavera Forest’s fumaroles, hot river and hot waterfall represent the last vestiges of vulcanism and are no cause for alarm. On the other hand, others, including Gail Mahood who has studied this area far more than most, warn that hazard monitoring is justified in the case of La Primavera given its proximity to a major city and bearing in mind that any future eruption would be likely to occur on the southern and/or eastern side of the caldera.

The La Primavera Forest is only one of several calderas in Mexico’s Volcanic Axis.

If you prefer a short 9 minute video animation of how the area was formed, try this excellent YouTube video: “The Exciting Geology of Bosque La Primavera“, produced by geologist Barbara Dye during her stint as a Peace Corps volunteer in Mexico.

References:

  • Mahood G. A. 1980. Geological evolution of a Pleistocene rhyolitic center – Sierra La Primavera, Jalisco, Mexico. Journal of Volcanology and Geothermal Research, 8: 199-230.
  • Mahood, G.A. 1981. A summary of the geology and petrology of the Sierra La Primavera, Jalisco, Mexico. Journal of Geophysical Research, Volume 86.
  • Dye, Barbara. 2013. “La Apasionante Geología del Área de Protección de Flora y Fauna La Primavera”.

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Mexico’s geomorphosites: the Primavera Forest, Guadalajara, Jalisco

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Jun 012013
 

The Primavera Forest (aka Bosque de la Primavera, Sierra de la Primavera) is a volcanic region located immediately west of Mexico’s second-largest city, Guadalajara. The Primavera Forest occupies an ancient volcanic caldera, where the last eruptions are thought to have been about 30,000 years ago. The Primavera is a wilderness area of pine and oak woodland, with hot-water rivers, nature-trails and thermal spas. The park, which is about 30 km (19 mi) across (see map), serves as the lungs of Guadalajara and is popular, especially on weekends, for activities such as picnics, birdwatching, hiking, climbing, mountain biking and motocross.

The Primavera Forest. Credit: Semarnat, 2003

Basic map of the Primavera Forest. The distance between Tala and Guadalajara is about 35 km (22 miles). Credit: Semarnat, 2003

The main geographic and geological attractions of the Primavera Forest include:

Scenery, views, flora and fauna

The average elevation of the Primavera Forest is about 2200 m above sea level, rising to 2270 m (7447 ft) towards the eastern edge of the forest which overlooks the city of Guadalajara. The three main summits are El Pedernal, San Miguel and Las Planillas. There is easy access to the 30,000 ha of protected natural area from various points, including the town of Tala and from Highway 15 (the main Guadalajara-Tepic highway) which skirts the northern edge of the Primavera. Agriculture and settlement have made incursions into the edges of the park, with land cleared for subdivisions or for fields of sugarcane and agave (for tequila). A major wildfire raged through parts of the forest in 2012.

The park is home to about 1000 different plant species as well as 137 different birds and at least 106 terrestrial animals, including deer, puma, opossums (tlacuaches), armadillos and rabbits.

Hot springs

Thermal springs are common throughout the Volcanic Axis of Mexico, and the hot river and many hot springs in the Primavera Forest are a legacy of its volcanic history. Río Caliente, the main developed spa in the Primavera Forest, famous for several decades as one of the country’s top vegetarian and health spas, closed in 2011, following some years of uncertainty regarding its land tenure status and increasing security concerns because of its relatively remote location.

The hot springs in the park have been subject to numerous exploratory studies by the Federal Electricity Commission (CFE) which considers the park a potential source of geothermal power. The CFE drilled a dozen wells in the 1980s, finding that six of them offered sufficient flow for power production. The CFE believes the park could support at least three 25 megawatt geothermal plants. Drilling was suspended between 1989 and 1994 when the Jalisco state government ordered the CFE to carry out environmental restoration to areas damaged by drilling activities, and the plants have not yet been approved.

Pumice deposits

As veteran explorer-author John Pint points out in “A geopark in my back yard?”, the Primavera Forest is well known to geologists for its giant blocks of pumice, up to several meters across, which are among the largest found anywhere in the world. One of the best locations for seeing these is in the 50-meter-high walls of the Río Seco arroyo on the northern edge of the park, on the outskirts of the small community of Pinar de la Venta. The cliff face has a thick band of pumice overlying numerous thin layers of lake sediments. The pumice blocks are highly vesicular (full of holes) and therefore surprisingly light for their size.

Obsidian deposits

The Primavera Forest is also well known to geologists (and archaeologists) because it has significant amounts of obsidian, a hard, glassy, usually black rock. Obsidian is easy to find (often in big chunks) in several parts of the park. The obsidian formed when blocks of hot lava, still molten, rained into the cold waters of a lake, cooling instantaneously. When fractured, pieces of obsidian acquire very, very sharp edges. Even today, some surgeons still prefer obsidian scalpel blades, recognizing that they are far sharper than those made from even the best steel.

Obsidian was in great demand in precolonial times for use as mirrors, arrowheads and knives, as well as jewelry:

“Among the people to prize obsidian were the residents of Iztépete (often spelt Ixtépete), “hill of obsidian or knife blades”, located just outside the eastern edge of La Primavera. This small, largely forgotten, and poorly-signed archaeological site in a southern suburb of Guadalajara is within a stone’s throw of the city’s periférico (ring-road).”

“Large, angular chunks of obsidian litter the slopes of Cerro Colli, the hill rising behind the 6-meter-high pyramid, which conceals at least five earlier pyramids, each superimposed over the one before. Ceramics found here suggest that occupation stretches back at least to the fifth century, but little is known about the people who built this site.”  [Quotes are from the recently published 4th edition of the author’s “Western Mexico, A Traveler’s Treasury”]

Obsidian is found throughout this region, and while usually black in color, it can also be found in a range of hues, including red and even rainbow patterns. Not far from the western edge of Primavera, at the foot of a steep-sided knoll called El Picacho is El Pedernal, reputed to be the largest obsidian deposit in the world, covering 4 square kilometers, from which an astonishing 40,000 cubic meters of rock have been extracted over the centuries. Sophisticated chemical techniques have shown that El Pedernal obsidian was widely used in Mesoamerica, finding its way as far north as California and as far south as Oaxaca!

The pre-Columbian obsidian jewelry from this region, consisting of very thin wafers of rock, is unique to this area, and clearly the work of highly skilled specialist craftsmen. One particularly fine example (now in the museum in Tala) is a necklace fashioned out of wafer-thin obsidian carvings of human figures, each pierced by a tiny hole. In the absence of metal tools, the patience and dexterity required to have made these is truly amazing.

The art of obsidian carving has not been lost. Skilled artisans in Navajas, another nearby village, continue to this day to chip and shape chunks of obsidian into spheres, chess boards and beautiful works of art, often representing animals.

In future posts we will consider the formation of the La Primavera Forest in more detail, and also look at the extent to which the pressures resulting from its proximity to the city of Guadalajara threaten the park’s long-term health.

Want to read more?

John Pint is one of those spearheading the proposal of seeking UNESCO designation for La Primavera as a GeoPark.

U.S. Peace Corps Volunteer and geologist Barbara Dye has written a beautifully-illustrated  72-page guide (in Spanish) to the geology of the Primavera Forest: “La Apasionante Geología del Área de Protección de Flora y Fauna La Primavera”.

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