Milam Glacier Trail - Landscapes

Earlier in the month from October 10th to October 18th, I walked the Milam Glacier trail in the Kumaon Himalaya, Uttarakhand. A four day walk through the Johar Valley from Lilam village near Munsiyari to Milam took me past some fantastic landscapes and geology. 

After an initial breathtaking climb which takes you from about 6000 feet at Lilam to more than 9,000 feet at a high ridge known as Mainsingh Top, the trail descends towards the Indo-Tibetan Border Police outpost at Bugdiyar. After this, a gradual ascent takes you higher, with the rest of the walk undulating between 10,000 to 11,000 feet ASL. I was lucky with the weather. After walking the first two days in belting bone chilling rain the skies cleared and I was treated to some gorgeous views of the High Himalaya. 

I am posting a few pictures of the landscapes along this scenic route. The pictures are roughly ordered from the start towards the end of the trail.

The Greater Himalaya near Bawaldhar, a small resting stop which we came across on the first day.

Another view of the Greater Himalaya in the vicinity of Bugdiyar. Notice the steep slopes, narrow valleys and the sheer rock faces and the cascading Goriganga river. 

A lovely rough trail near the Laspa area. The October colors really makes the landscape radiant. 

After Laspa, the Greater Himalaya made up of high grade metamorphic rocks give way to the low grade metamorphic and sedimentary terrain of the Tethyan Himalaya. You do notice a change in the topography from the sheer steep slopes and narrow valleys typical of the Greater Himalaya to the wider valley forms and gentler gradients of the Tethyan domain. 

The Goriganga at Rilkot. The river is more serene here making a soothing gurgling sound as it flow past. Also check out the gorgeous longitudinal gravel bars in the river channel. Permanent Link: Goriganga at Rilkot.  

The high meadows of Martoli. This is a beautiful if desolate place with stunning views of the high Himalayan all around. 

A lone resident of Burfu surveys his kingdom. Most of the villages were empty of people as residents had migrated to lower altitudes for the winter. The flat plateau seen in the background is a glacial outwash terrace. It was formed by streams redepositing debris that accumulates in front of a glacier. Thick layered river deposits create a plain in front of the glacier. At a later point in time, the river cut through its own deposits, forming flat terraces stranded high on the valley slopes. 

Encounter on a lonely trail. After walking alone for hours, it is always fun to meet the locals travelling between villages. We met this small caravan between the settlements of Burfu and Bilju. Permanent link: Encounter at Bilju.

 A house in Milam village basks in the October sun. 

The Goriganga snakes its way down Milam Glacier through the fabled Johar Valley. This location is a few kilometers downstream of the glacier. 

Near Milam Glacier! The actual glacier is about 4-5 km upstream of this location, but this is a good photo spot along the trail.

What a trip! I think late September to early October is really the best time to visit this area. The countryside is lush and you get clear views of the Himalaya. The local residents have still not migrated to lower altitudes and you can get to enjoy their company in the many hamlets along the way. However, this year, rains continued well into the second week of October. I feel with climate change there will be a greater unpredictability to October weather in the future.

Finally, a big thank  you to Emmanuel Theophilus, Malika, Kamala Pandey, and Munna Singh Nitwal for being such gracious hosts and making my trip so memorable.

A post on geology tips for trekkers is coming soon... 

Readings: Earth's Ice, Neanderthal Women, Indian Monsoons

Some good stuff from the past few weeks.

1) How much of the Earth's Ice is Melting? Sid Perkins writes about the variety of methods of estimating ice loss from the high latitudes. These methods are showing where and how much melting is taking place, in turn, helping scientists make predictions of future sea level rise. The overall scenario is rather gloomy. 

2) The Lives of Neanderthal Women. "Archaeology is no exception to biases against women’s interests across science and the humanities". Archaeologist Rebecca Wragg Skykes expertly constructs a picture of what the lives of Neanderthal women might have been like.

3) Indian Monsoon Across Millennia. Stalagmites from a cave in Meghalaya, NE India are giving paleoclimatologists information about monsoon variability over a thousand years. Their geochemistry points to periodic deadly droughts that coincide with phases of major social and political turmoil in India. Paper authors Gayatri Kathayat and Ashish Sinha describe their research. 

 

LInks: India Aquifers, Early Bipedalism, Mars Geology

 Here are some interesting articles I read recently.

1) Mapping India's Aquifers.  Indian agriculture depends heavily on groundwater. To understand and manage this resource we need a good idea of the nature and extent of aquifers. Subodh Yadav, Joint Secretary, Department of Water Resources, River Development and Ganga Rejuvenation, Ministry of Jal Shakti, has written an informative article on the National Aquifer Mapping Program. Detailed reports are available to the public through the Central Ground Water Board, Aquifer Information and Management System page. Mapping and report availability is still work in progress.

2) Is Sahelanthropus the earliest biped? A good article by Brian Handwerk on the many questions spawned from a recent analysis of a 7 million year old femur fossil. Fossil remains named Sahelanthropus tchadensis were found nearly 20 years ago in Chad, and various studies have come to conflicting conclusions on whether Sahelanthropus could walk on two legs. Bipedalism is considered to be one of the key traits distinguishing members of the human branch from other apes and so there is a vital interest in understand the timing and circumstances of its evolution. 

3) Ground Penetrating Radar images from Mars Perseverance Rover. The indefatigable Mars Rover loaded with geological instruments is currently exploring the edge of the Jezero Crater on Mars. Here, rivers emptied into a large lake depositing sediment and building a delta. The first radar images show inclined sedimentary layers which could be the classic sign of a delta architecture or something else, scientists suspect. Read on! By Holly Ober, University of California, Los Angeles.

Readings: Deep Time Mexico, Neanderthals, Early Mammals

Relish these articles.

1) Mexico City Deep Time Sickness.  Modern day Mexico City is built on the bed of lakes that formed around 2 million years ago. The Mexica people in the 14th century constructed a series of dams and dykes partitioning salt water and fresh water areas. They developed agriculture called as 'chinampas' on islands made up of mud and organic debris. This region became the city state of Tenochtitlan. Later in the 16th century this vast lake was drained by Spanish Conquistadors. Over time, extraction of groundwater is causing compaction of the soft sediment. The ground is subsiding unevenly across different parts of the city. Ground shaking by frequent earthquakes is making the problem worse. As cracks grow and widen, buildings tilt, and the ground shakes, the citizens have become acutely sensitive or "tocado" to geology altering their everyday lives.

"Deep time is often framed as something antithetical to immediacy, something totally separate not only from everyday experience, but also the idea of history itself. But if we are living in a moment in which experiential time, historical time and deep time are colliding, which of these times are being written onto the walls of Mexico City apartments?" 

A beautiful and unnerving article by Lachlan Summers.

2) Did Neanderthals Speak? Archaeologist Anna Goldfield summarizes our current state of understanding of the throat anatomy of Neanderthals and how they might have sounded. There is a nice audio clip too! 

3) Warm Blooded Mammals. When did warm bloodedness or endothermy evolve in mammals? Katherine Irvine writes about a new study of ear canal bone structures indicative of endothermy. An analysis of fossils suggest that warm bloodedness, along with a host of traits typically associated with mammals, arose by around 233 million years ago. 

Field Photos: Italy Swiss Alps

A friend recently went for a trek to the Italian and Swiss Alps and sent me these stunning photos.

All Alps pics by Dr. Sushma Date.

A view along the Santa Magdalena or the Alp Suisse trail.

Imposing Pinnacles along the Tre Cime di Lavaredo hike in the Italian Alps.

 A close up of limestones and dolomites in the Italian Alps.

 A panoramic view of the distinctive landscape along the trail.

There is so much to see here in terms of geomorphology and how glacial erosion throughout the Quaternary Period has carved out the terrain. But my friend was also walking past rock outcrops that stand witness to one of the most enduring debates in sedimentary geology: the origin of that distinctive layering in these sediments.

The section of the Alps my friend was trekking in is made  up of Middle to Late Triassic age (225 -200 million years ago) limestones and dolomites. They formed in the warm tropical waters of the western Tethys Ocean. A closer examination of the layering reveals that the sediments were deposited in two broad subenvironments of a shallow sea, the intertidal zone and the subtidal zone. Intertidal and subtidal sediments alternate to form a depositional pulse or a cycle. Such couplets are stacked to form the thousands of feet of strata observed in this part of the Alps.

What could be causing the alternation of the intertidal and subtidal environments? Thick intervals of these Triassic deposits are made up tidal mud flats overlain by restricted lagoon sediments, or tidal mud flat overlain by open circulation subtidal environments, or lagoon deposits overlain by mud flats. When beds are traced laterally, these same environments grade into each other. Such inter-fingering arrangements suggest that environment adjacent to each other migrate, resulting in a vertical succession of alternating sediment types.  

Geologists recognize that such changes can be 'áutocyclic', driven by mechanisms internal to the sedimentary basin. A site of biological productivity and sediment production may choke itself by overproducing sediment. The loci of sediment production may shift to a more favorable site. Episodic storms keep redistributing sediment and reorganizing current directions . Such feedbacks result in similar environments appearing and disappearing from any one location, resulting in a cyclic sedimentary record. 

There are also successions of strata in the Triassic Alps which show a very different arrangement of sediment types. In this variation of cyclicity, intertidal mud flats may be overlain by relatively deeper water subtidal sediments which in turn are overlain by a red soil layer. The formation of soil on top of subtidal sediments deposited in water depths of up to 10 meters or so indicates a substantial drop in sea level. The top of the exposed subtidal layer was then chemically weathered to form a soil. 

Autocylic shifts in environments are gentle nudges which push one environment over another. They can't generate such a big drop in sea level. There must be drivers external to this environment that may cause sea level to rise and fall at regular intervals. These external agencies or  'allocyclic' mechanisms have been invoked to explain parts of these Triassic sequences. 

What could be controlling the regular rise and fall in sea level? Long term (over millions of years) tectonic subsidence of the basin floor certainly would have created the accommodation space for the accumulation of sediment. However, geologists look toward a different mechanism to explain the repeated deepening and shallowing events observed in these Triassic strata. 

Climate change can cause regular shifts in sea level. During the past 2.6 million years of the Quaternary ice age, sea levels have fallen by as much as 100 meters during phases of continental glacier growth, and risen during inter-glacial times when ice sheets melt. These changes have taken place at intervals of 400,000 years in the early part of the Quaternary, changing to beats of 100,000 years over the past million years. Sea level changes due to growth and decay of continental glaciers are termed glacio-eustacy. Unlike autocycles which can have variable time spans, there is a fixed periodicity to these climate driven allocycles. 

We now know that these climate cycles are controlled by periodic changes in the earth's orbital parameters which cause cyclic variation in the amount of incoming solar radiation. Such Milankovic glacio-eustatic cycles, named after the Serbian mathematician who worked out the details of earth's orbital behavior, have been recognized during other times of widespread glaciation such as the Permian. 

Milankovic worked out that there are three types of orbital movements that affect how much solar radiation reaches the top of earth's atmosphere. The shape of the earth's orbit or eccentricity cyclically varies with a period of 100,000 years and with a longer period of 400,000 years. Obliquity, or the tilt of the earth's axis with respect to its orbital plane, changes every 40,000 years. The third type are Precession cycles of 26,000 years. This is the wobble or the direction the earth's axis points to.

The Triassic though was a very hot world! The earth's land masses, amalgamated in the supercontinent Pangaea, were situated across the equator. There were no continental glaciers to wax and wane and drive sea level change. Glacio-eustacy is not a workable explanation for these cyclic Alpine sedimentary sequences.

Of late many geologists have started pointing to groundwater storage in continental aquifers as a means of causing periodic sea level change. It does sound like a fantastical idea! Such groundwater mediated sea level changes go by the name of aquifer eustacy. Milankovic climate cycles may not trigger glaciation during hot earth periods. But they can modulate long lasting humid and arid phases, each lasting tens of thousands of years. Sea levels are lowered during hot humid phases as oceans lose water by evaporation while continental aquifers get recharged. During arid phases, water is lost from aquifers by evapo-transpiration and discharge, resulting in a rise in sea level. 

An inverse phase relationship between groundwater level and sea level is thus an expectation of aquifer eustacy.

There is enough water in continental aquifers to modulate sea level change of several meters. Here is an impressive statistic. There is approximately 25 million cubic kilometer of pore space in the upper 1 km of continents above sea level.  If this is completely filled with water, the amount will equal the volume of water in continental ice caps. Even a small fraction of these pore spaces actually getting filled with water or emptying of it can change sea levels by several meters. 

Recent short term measurements of the hydrological cycle supports the notion that groundwater storage can influence sea level. For example, very high rainfall over Australia and part of the southern Hemisphere in 2011 resulted in a drop of 7 mm in global sea level that lasted a few months. And the Gravity Recovery and Climate Experiment satellite data since 2002 indicates that increased land water storage has actually slowed down the rate of sea level rise by a small amount.

Can some of the Triassic sedimentary cycles of the Alps be attributed to aquifer eustacy? How can one track periodic groundwater change in geologic history and test whether they coincide with sea level changes? One proxy is to use lake sediments of the same age as marine sequences.  Lakes are connected to aquifers.  High lake levels are indicators of saturated aquifers. Lake levels drop as aquifers discharge. Geologists have been studying Late Triassic age lake sediments from the Newark Basin in  northeastern U.S. They have identified sedimentary cycles formed during alternating humid (high lake levels) and arid climate (low lake levels) phases. 

The broad time span of these lake sequences coincide with the time frame of some thick intervals of marine sedimentary cycles of the Alps. Whether individual lake and marine cycles are out of phase could not be worked out due to limitations in age resolution of strata. However, a Milankovic band 400,000 year periodicity has been estimated for these cycles, a finding strongly suggestive of  climate driven eustacy.  From another time period, some analysis of  Cretaceous age lake sediments of Songliao Basin of NE China indicated lake level highs coinciding with global sea level lows. This finding also hints that aquifer recharge and discharge may be primarily responsible for periodic sea level changes during a greenhouse earth when there are no continental glaciers to modulate sea levels. 

Such questions continue to be asked and the mechanisms behind generating sedimentary cycles of the Triassic has by no means been satisfactorily worked out. There are many types of cycles in the Triassic Alps, observed R.A. Fischer, whose seminal work in the 1960's opened up avenues of debate that continue unabated. Perhaps it is the spectacular setting and stark rock faces that lend themselves to bold hypothesis making, linking sedimentary rhythms to the celestial dance of our planet.