During my recent trek in the Goriganga valley, I noticed steep hillsides and plenty of landslides. There are a number of geological attributes of this region that makes hill slopes susceptible to fail.
The rocks dip steeply - in this region towards the north. These are medium to high grade metamorphic rocks. They are foliated, that is made up of platy and flaky minerals like biotite, muscovite, chlorite and amphiboles. Because of this, slabs of rock cleave off the plane of foliation. The picture below shows a phyllitic rock with a pervasive north dipping foliation. You can see large slabs of rock flaking off the surface forming small rock falls.
Some layers of rocks are fractured. The picture below shows bands of calc-silicates i.e. clay bearing limestones which have been metamorphosed. The rocks are shattered by intersecting fractures, and blocks fall off the main body of rock. Something else (tremor, heavy rains) must have triggered this major rock fall.
Sometimes soil, shrubs and tree covered slopes may give way like the one pictured below. Again, heavy rains or tremors may trigger this failure.
Add to these natural properties that make the rocks susceptible to breaking, and hillslopes unstable, is the increase in road building activity. Blasting rock faces with dynamite and bulldozers and heavy vehicle traffic result in constant vibrations and small tremors. We started our trek a little north of Dhapa. The picture below shows roads being hacked out of very steeply sloping hillsides.
Another view of a rock cut in a precipitous hill slope, with a great backdrop of north dipping high grade metamorphic rocks.
Small landslides and rock falls are common along these road sections. Here is a picture of remediation measures being taking; in this case a stone wall..
A view of a large slump between the villages of Kuri (on the left) and Jimia (on the right).
A view of two landslides with a terrifying look down towards the river Goriganga. The major rock fall in calc-silicate rocks I described above and across the valley, along a road being built between Munsiyari and Milam glacier.
Debris from landslides choke streams and rivers. The picture below shows ponding in the Ramganga river due to excess sediment brought in by numerous landslides along this stretch of road.
The river bed has to be dredged. Here a channel in the Ramganga river bed has been excavated. Sand miners are also busy at work.
Another look at that scary rockfall in the calc-silicate gneisses, with a rough path through it.
The rocks dip steeply - in this region towards the north. These are medium to high grade metamorphic rocks. They are foliated, that is made up of platy and flaky minerals like biotite, muscovite, chlorite and amphiboles. Because of this, slabs of rock cleave off the plane of foliation. The picture below shows a phyllitic rock with a pervasive north dipping foliation. You can see large slabs of rock flaking off the surface forming small rock falls.
Some layers of rocks are fractured. The picture below shows bands of calc-silicates i.e. clay bearing limestones which have been metamorphosed. The rocks are shattered by intersecting fractures, and blocks fall off the main body of rock. Something else (tremor, heavy rains) must have triggered this major rock fall.
Sometimes soil, shrubs and tree covered slopes may give way like the one pictured below. Again, heavy rains or tremors may trigger this failure.
Add to these natural properties that make the rocks susceptible to breaking, and hillslopes unstable, is the increase in road building activity. Blasting rock faces with dynamite and bulldozers and heavy vehicle traffic result in constant vibrations and small tremors. We started our trek a little north of Dhapa. The picture below shows roads being hacked out of very steeply sloping hillsides.
Another view of a rock cut in a precipitous hill slope, with a great backdrop of north dipping high grade metamorphic rocks.
Small landslides and rock falls are common along these road sections. Here is a picture of remediation measures being taking; in this case a stone wall..
A view of a large slump between the villages of Kuri (on the left) and Jimia (on the right).
A view of two landslides with a terrifying look down towards the river Goriganga. The major rock fall in calc-silicate rocks I described above and across the valley, along a road being built between Munsiyari and Milam glacier.
Debris from landslides choke streams and rivers. The picture below shows ponding in the Ramganga river due to excess sediment brought in by numerous landslides along this stretch of road.
The river bed has to be dredged. Here a channel in the Ramganga river bed has been excavated. Sand miners are also busy at work.
Another look at that scary rockfall in the calc-silicate gneisses, with a rough path through it.
