Showing posts with label field work. Show all posts
Showing posts with label field work. Show all posts

Saturday, November 4, 2017

Explore Fascinating Geology of Lofoten Islands, Norway

It is probably going to be boring what you are going to read, but if you are a geologist, please continue reading.
 What started as a simple fun trip with some friends to Lofoten Islands in northern Norway, just became a unique geological experience. This, because I think that, as a geologist, it is completely impossible to separate fun from my profession while traveling. It's just amazing to mix your profession with your favorite hobby. 
Trying to understand the rocks, the configuration of the landscapes and their phenomena, is simply priceless.
Reinebringen Mountain, Norway.
View to the town of Reine and Fjords.
Photo Credits: J. Sebastian Guiral
This time I got completely impressed with the beauty of the Fjords in Lofoten (help: what is a fjord? well basically, a fjord is a narrow and deep channel that allows the sea to enter to the land. They can be several kilometers long, so they are often confused with rivers or lakes, and can reach great depths, exceeding 1000 m. These geomorphological units are the product of sea flooding of valleys created by glacial activity).
Reinebringen mountain, Reine, Norway.
View to the town of Reine and Kirkefjord. U-shaped valleys and geomorphological features associated with intense tectonic activity. Glacial lake
Photo Credits: J. Sebastian Guiral
Hiking through the perfectly carved U-shaped valleys left me speechless (above mentioned glacial valleys). In each valley, it was possible to appreciate the sediments associated with the activity of the glacier, that is, the Moraines (frontal and lateral), till and reworked proglacial sediments.

Skelfjord, Lofoten, Norway.
Photo Credits: J. Sebastian Guiral



In addition, the typical vegetation of Tundra is impressive (help: what is Tundra? In simple words, it is a biome characterized by the lack of trees, the soils are mainly covered with mosses and lichens, characteristic of circumpolar latitudes. The subsoil is almost permanently frozen). This vegetation covered the base of the mountain chains and snowy hills, contrasting in a perfectly artistic way and offering a breathtaking view. 
Å, Moskenes, Norway.
Mosses on Precambrian gneisses and migmatites.
Photo Credits: J. Sebastian Guiral
Reine, Lofoten Norway.
View to Reinefjorden and snowy peaks
Photo Credits: J. Sebastian Guiral
Hamnøy, Lofoten Norway. Snowy Peaks.
Photo Credits: J. Sebastian Guiral
Haukland beach, Leknes, Lofoten, Norway

Snowy Peaks at Hamnøy, Lofoten Norway.
Photo Credits: J. Sebastian Guiral
What about lithologies? Well, broadly all those landscapes are conformed by a Precambrian basement represented by an Archean and Paleoproterozoic metamorphic complexes of ortho- and paragneisses, intruded by anorthosites and suites of charnokite-granites. This basement is in tectonic contact with amphibolites and paragneisses, which were intruded by tonalitic magmas at 470 Ma. Subsequently, at the top of the sequence, in a rather complex structural context, volcano-sedimentary sequences are found, ranging from the Permian to the Paleogene. These volcano-sedimentary sequences are part of the sea floor between Greenland and Norway. All these units are in well-marked tectonic contacts.

Utakleiv Beach, Leknes, Lofoten, Norway.
Paleoproterozoic amphibolites and gneisses.
Photo Credits: J. Sebastian Guiral
Utakleiv Beach, Leknes, Lofoten, Norway.
Paleoproterozoic amphibolites and gneisses
Photo Credits: J. Sebastian Guiral 

Paleoproterozoic amphibolites and gneisses at Haukland beach, Leknes, Lofoten, Norway
Photo Credits: J. Sebastian Guiral 

Finally, in addition to the geological stuff, the sunsets, perfect beaches, rainbows, snowstorms, the strong rain and a whole bunch of climatic phenomena associated with these high latitudes, make the Lofoten Islands one of the places. I have enjoyed a lot being a geologist. 

Reine, Lofoten Norway.
View of Reinefjorden and snowy peaks
Photo Credits: J. Sebastian Guiral 

 This is what I like about this profession, trying to understand a bit about such a complex, beautiful and huge planet.

If you are a geologist and feel the same as me while traveling, let me congratulate you.
You have a beautiful profession!
Sebas enjoying rain in Å, Moskenes, Norway.
Photo Credits: J. Sebastian Guiral 
  
Sebas exploring Paleoproterozoic amphibolites and gneisses at Utakleiv Beach, Leknes, Lofoten, Norway.
Photo Credits: J. Sebastian Guiral 
About authorJ. Sebastian Guiral is a Geological Engineer from the National University of Colombia. He is currently pursuing his master's program in Georesources Engineering at the Luleå University of Technology in Sweden. He also has  studied at the University of Liege in Belgium and at University of Lorraine in France. As a geologist, he has worked in important engineering and research projects in his country, which include geomechanics of underground excavations, geodynamics and geomorphology. Currently, his interests are focused on economic geology, exploration, mining and mineral processing techniques. 
You can contact with J. Sebastian Gujral at [email protected] or at Instagram: @sebasguiralv

We are grateful to J. Sebastian Gujral for sharing his knowledge and adventures with us. You can also contribute share your geological adventures with us. See details here.

Friday, August 25, 2017

Recorded Live-Virtual field tour of Cajon, California and the San Andreas Fault



Recorded Live-Virtual field tour of Cajon, California and the San Andreas Fault:




This "Live-Virtual Field Tour" was the part of our outreach project. Please contribute and help us to help others. Read details of the project here.

Thursday, July 27, 2017

"Why I left Electrical Engineering and choose Geology?" with Rana Faizan

About author: Rana Faizan is currently in his third year of under graduation in Applied Geology at Institute of Geology at University of the Punjab in Lahore, Pakistan. He is interested in Petroleum Geology, Structural Geology, Sedimentology and Tectonics.         
  

When I was studying in the 8th grade, my father had a wish to make me an Electrical Engineer. Honestly speaking at that time I have no idea about my future goals and even I didn’t knew anything about Electrical Engineering.
One day I was in my class, my teacher gave us a lecture on future planning which really inspired me to think about future aims. This was the first time I started thinking about my future goals. I reached home and asked my father about this concern. He advised me to choose Electrical Engineering in future and told me that this is his dream about me. At that time, I was not familiar with the Geology. Days were passed and I completed my 10th grade exams with good percentage and took admission in 11th grade (pre-engineering), and I started study hard to fulfill my parent’s dream.

Then a day come, my father was sharing his university life experiences with me and this was the first time I heard about Geology because his hostel mates were Geology students. My father told me about the geology field work experience that his friends shared with him. And his friend is currently settled in Canada and working as a Geologist. He told me about some more people and some of them are now my professors.

These all things sums up and gave me inspiration about geology, I searched about geology on internet and I found it an interesting field as geologists ruin tourism in their daily life. They can work in natural resource companies, environmental consulting companies, government agencies, non-profit organizations, and universities. Many geologists do field work at least part of the time. Others spend their time in laboratories, classrooms or offices. All geologists prepare reports, do calculations and use computers. I found that geology is a practical and professional field, all sciences and engineering required geology work in some disciplines. Another thing is the study of mountains, different rocks, minerals, structures and more over their observations in field with naked eye is so interesting. Moreover thin section study and geological mapping was another cause that inspired me to pursue my career in this field.

Due to all these things, I mentally prepared myself to choose geology in future but my father wanted me to become an engineer.

After few months, I completed my 12th grade with good percentage and I applied for electrical engineering as per my father’s wish. And I also applied for geology as per my wish. Unfortunately, I didn’t get admission in any geology institute and get admission in electrical engineering. My parents were very happy because their wish was near to fulfill at that time but I was not so happy because I wanted admission in geology. Then unwillingly, I have to study the electrical engineering. This was little bit interesting subject for me especially circuits. I liked working on C++ programming. I completed my first semester with good CGPA and got 2nd position but still I wasn’t satisfied in this field. 

Next year, when I was studying 2nd semester in engineering, the admissions in geology get opened and again I tried to get admission in this field but my parents, relatives and friends even my engineering professors advised me that I should not leave this field (engineering) now because that decision would effected my future and one year of my study would be wasted. I listened to my heart voice and applied for admission and I was surprised to know that I got admission in geology. I left engineering and join geology field. My friends and professors of engineering institute asked me again not to leave this field. I still remembered, I simply told them that I don’t want high marks, I want to fulfil my interests so that I can give my 100% in that work. I thought what if I done electrical engineering with good percentages and get job. But what if I am not satisfied with my decision then what is the benefit of that job? Geology may not give me highly paid jobs easily as I could find in electrical engineering but I would definitely find peace and satisfaction in geology.


Me (left) discussing geological map of Pakistan with my class mate (right).
Photo © Rana Faizan 
Describing about Salt Range (Sub-Himalayas) model
Photo © Rana Faizan 
Now, I’m studying geology and I am fully satisfied with my decision. I have completed my two and half years of bachelor’s degree with three field works and I have learnt many things about geology. I found all things as same as I imagined, when I was in 12th grade. This was my dream that one day I will become a geologist and will study from the same institute from my father’s friends have studied. Everyone has its own interest. Some like engineering, some like medical and some go for other. My purpose here is not to degrade anyone especially electrical engineering students, no doubt it is also a good field as technology is becoming a need of everyone. So, I have an advice for everyone, always listen to your own decisions and do not bother what other say.

Selfie at Harno River, Abbottabad, Pakistan.
Photo © Rana Faizan 
Had a rainy fieldwork at Indus River, Pakistan
Photo © Rana Faizan 
I still remember a quote:
                    "Think 100 times before you take a decision,
But once that decision is taken, stand by it as one man."

We have a lot of hidden potential that we don’t know. And if we know then we don’t utilize it because we fear what people would say. More than that there is our own voice shouting inside that you can do this. What if we stop listening to those voices and listen only to our heart.
I have observed many geological things during field work and some pictures below are describing about the beauty of geology. I have many pictures related to rocks, minerals, structures and other features. Some beautiful pictures are given below:
Hammering slates
Photo © Rana Faizan 
Plunging anticline fold observed during fieldwork.
Photo © Rana Faizan


 
Enjoying fieldwork after mapping sedimentary area
Photo © Rana Faizan 

Note: This article is originally written and contributed by Rana Faizan. You can also contribute your article by sending us at [email protected]. We would love to share your field experiences with our readers. See guidelines here.




Sunday, April 30, 2017

Equipment for Geological Field Work

Following is a list of all equipment that is likely to be needed in the field:

1. Adhesive tape
2. Aerial photographs
3. Altimeter
4. Binoculars
5. Calculator
6. Camera, tripod, film, etc
7. Chemicals for staining rocks
8. Cold chisel
9. Color pencils
10. Colored tape or paint for marking localities
11. Brunton compass or other
12. Drawing Board
13. Erasers
14. Field case for maps and photographs
15. Field glasses
16. First aid kit
17. Flashlight
18. Gloves
19. Gold pan
20. Grain-size card
21. Geologists Hammer
22. Hand lens
23. Dilute Hydrochloric Acid
24. Ink, waterproof; black, brown, blue, red and green
25. Insect repellent
26. Jacob staff
27. Knapsack
28. Lettering set
29. Loose-leaf blinder
30. Magnet
31. Maps, topographic, geologic
32. Microscope
33. Mineral hardness set
34. Field notebooks
35. Paper, lined
36. Paper, quadrille
37. Paper, scratch
38. Pen, drop circle
39. Pen, holders
40. Pen, ruling
41. Pens, ballpoint
42. Pen, inkflow, for photographs
43. Pencils, 3B to 9H
44. Pencil pointer
45. Pick or mattock
46. Pocket knife
47. Protractors
48. Rain gears
49. Rangefinder, Camera
50. Reference library
51. Sample bags
52. Scale, plotting, 6 in.
53. Shovel
54. Stereo-graphic net
55. Tally counter
56. Tape, 6-ft
57. Tape, 100-ft
58. Triangles, drawing
59. Satellite phone
60. Watch

Estwing Hammer and Hand lens


A hammer with a pick or chisel end is used for cleaning exposures, for digging, for breaking rocks, and for trimming samples. Standard geologists hammer have heads weighing 1.5 to 2 lb (0.68 to 0.9 kg) and are adequate for most geologic work. A small sledge--- for example a 2 or 3 lb head on a 14-in. handle may be needed to collect fresh  samples of especially hard rocks.
While using hammer, it is important,
1. to wear safety goggles
2. not to strike heavy blows when people are nearby
3. never to strike one angular rock edges

A cold chisel maybe used with a hammer to split rocks parallel to bedding or foliation and to free fossils or specific mineral samples from unfoliated rocks.

A map holder must be large enough to carry 9*9 in. aerial photographs and should be made of masonite rather than metal( which in uncomfortable to carry) or plastic (which may break when cold).

A scale, used for measuring features or laying off distances on maps and photographs, should have fine, distinct graduation marks that are equivalent to even increments at the map scale used.

A protractor is used for plotting structural symbol maps and for measuring angles between structures in rocks.

A camera, for, photo-geologic interpretation, is an important equipment for geological field work and should be compact and strong. All 35 mm cameras have a great depth of focus than cameras with longer focal length and this is a decided advantage in photographing irregular outcrops at closer range.

Samples bags of cloth or plastic maybe obtained through most suppliers, or bags maybe of extra heavy paper, the variety often used as nail bags.

Hydrochloric acid will be needed and should be diluted just to the strength that causes effervescence of calcite but not dolomite (except when powdered).

Of the hand lenses, 10X and 14X lenses are used most widely. The depth of focus of the 14X lens, however, is only 0.8 mm, whereas that of 10X lens is 2.5 mm.
Good quality triplet lenses typically give excellent images. In testing a lens, and in all other viewing, the following are important:

1. Hold the sample so that the area being viewed is in full light --- in sunlight, if possible.
2. Hold the lens exactly at the distance of sharp focus, with its optical axis perpendicular to the surface being viewed
3. Bring the eye to the point where the eyelashes are mostly touching the lens (this is the only position from which the entire field of view will be sharply and comfortably in focus)


Sunday, April 23, 2017

Geologic Contacts

A geologic contact is where one rock type touches another. There are three types of geologic contact:1. Depositional contacts are those where a sedimentary rock (or a lava flow) was deposited on an older rock
2. Intrusive contacts are those where one rock has intruded another
3. Fault contacts are those where rocks come into contact across fault zones.
Learn in detail about fault here

Following are the some pictures showing each type of geologic contact

Depositional Contacts

1. Angular Unconformity, Siccar Point, Scotland

This place is known as Siccar Point which is the most important unconformity described by James Hutton (1726-1797) in support of his world-changing ideas on the origin and age of the Earth.
Here 
gently sloping strata of 370-million-year-old Famennian Late Devonian Old Red Sandstone and a basal layer of conglomerate overlie near vertical layers of 435-million-year-old lower Silurian Llandovery Epoch greywacke, with an interval of around 65 million years.


2. Cretaceous Sandstone overlying Conglomerate    Kootenai Formation, SW Montana

Photo Courtesy: marlimillerphoto.com

3. Dun Briste Sea Stack, IrelandDun Briste is a truly incredible site to see but must be visited to appreciate its splendour. It was once joined to the mainland. The sea stack stands 45 metres (150 feet) tall.

Dun Briste and the surrounding cliffs were formed around 350 million years ago (during the 'Lower Carboniferous Period'), when sea temperatures were much higher and the coastline at a greater distance away.  There are many legends describing how the Sea Stack was formed but it is widely accepted that an arch leading to the rock collapsed during very rough sea conditions in 1393. This is remarkably recent in geological terms

Photo Courtesy: dunbriste.com 


Fault Contacts

1. Normal Faulting in the Cutler Formation near Arches National Park

Photo Courtesy: travelinggeologist.com

2. Normal Fault in Titus Canyon, Death Valley, California 

Photo Courtesy: travelinggeologist.com


3. 
Horst and Graben Structure in Zanjan, Iran

Photo Courtesy: Amazhda

Intrusive Contacts 

1. 
Pegmatite and aplite dikes and veins in granitic rocks on Kehoe Beach, Point Reyes National Seashore, California.


2. Spectacular mafic dyke from Isla de Socorro from Pep Cabré. The Isla de Socorro is a volcanic island off the west coast of Mexico and it is the only felsic volcano in the Pacific Ocean

Photo Courtesy: travelinggeologist.com

3. The margins of this Granite dyke cooled relatively quickly in contact with this much older Gabbro.
Photo near Ai-Ais Namibia

Photo Courtesy: travelinggeologist

Saturday, January 28, 2017

Banded-iron formations (BIFs) - Evidence of Oxygen in Early Atmosphere

Our knowledge about the rise of oxygen gas in Earth’s atmosphere comes from multiple lines of evidence in the rock record, including the age and distribution of banded iron formations, the presence of microfossils in oceanic rocks, and the isotopes of sulfur.
However, this article is just focus on Banded Iron Formation.

BIF (polished) from Hamersley Iron Formation, West Australia, Australia

Summary: Banded-iron formations (BIFs) are sedimentary mineral deposits consisting of alternating beds of iron-rich minerals (mostly hematite) and silica-rich layers (chert or quartz) formed about 3.0 to 1.8 billion years ago. Theory suggests BIFs are associated with the capture of oxygen released by photosynthetic processes by iron dissolved in ancient ocean water. Once nearly all the free iron was consumed in seawater, oxygen could gradually accumulate in the atmosphere, allowing an ozone layer to form. BIF deposits are extensive in many locations, occurring as deposits, hundreds to thousands of feet thick. During Precambrian time, BIF deposits probably extensively covered large parts of the global ocean basins. The BIFs we see today are only remnants of what were probably every extensive deposits. BIFs are the major source of the world's iron ore and are found preserved on all major continental shield regions. 

Banded-iron formation (BIF)
is 
consists of layers of iron oxides (typically either magnetite or hematite) separated by layers of chert (silica-rich sedimentary rock). Each layer is usually narrow (millimeters to few centimeters). The rock has a distinctively banded appearance because of differently colored lighter silica- and darker iron-rich layers. In some cases BIFs may contain siderite (carbonate iron-bearing mineral) or pyrite (sulfide) in place of iron oxides and instead of chert the rock may contain carbonaceous (rich in organic matter) shale.

It is a chemogenic sedimentary rock (material is believed to be chemically precipitated on the seafloor). Because of old age BIFs generally have been metamorphosed to a various degrees (especially older types), but the rock has largely retained its original appearance because its constituent minerals are fairly stable at higher temperatures and pressures. These rocks can be described as metasedimentary chemogenic rocks.



                     Jaspilite banded iron formation (Soudan Iron-Formation, Soudan, Minnesota, USA
Image Credits: James St. John



In the 1960s, Preston Cloud, a geology professor at the University of California, Santa Barbara, became interested in a particular kind of rock known as a Banded Iron Formation (or BIF). They provide an important source of iron for making automobiles, and provide evidence for the lack of oxygen gas on the early Earth.

Cloud realized that the widespread occurrence of BIFs meant that
the conditions needed to form them must have been common on the ancient Earth, and not common after 1.8 billion years ago. Shale and chert often form in ocean environments today, where sediments and silica-shelled microorganisms accumulate gradually on the seafloor and eventually turn into rock. But iron is less common in younger oceanic sedimentary rocks. This is partly because there are only a few sources of iron available to the ocean: isolated volcanic vents in the deep ocean and material weathered from continental rocks and carried to sea by rivers.


Banded iron-formation (10 cm), Northern Cape, South Africa.
Specimen and photograph: A. Fraser
Most importantly, it is difficult to transport iron very far from these sources today because when iron reacts with oxygen gas, it becomes insoluble (it cannot be dissolved in water) and forms a solidparticle. Cloud understood that for large deposits of iron to exist all over the world’s oceans, the iron must have existed in a dissolved form. This way, it could be transported long distances in seawater from its sources to the locations where BIFs formed. This would be possible only if there were little or no oxygen gas in the atmosphere and ocean at the time the BIFs were being deposited. Cloud recognized that since BIFs could not form in the presence of oxygen, the end of BIF deposition probably marked the first occurrence of abundant oxygen gas on Earth (Cloud, 1968).
Cloud further reasoned that, for dissolved iron to finally precipitate and be deposited, the iron would have had to react with small amounts of oxygen near the deposits. Small amounts of oxygen could have been produced by the first photosynthetic bacteria living in the open ocean. When the dissolved iron encountered the oxygen produced by the photosynthesizing bacteria, the iron would have precipitated out of seawater in the form of minerals that make up the iron-rich layers of BIFs: hematite (Fe2O3) and magnetite (Fe3O4), according to the following reactions:
4Fe3 + 2O2 → 2Fe2O3
6Fe2 + 4O2 → 2Fe3O4
The picture that emerged from Cloud’s studies of BIFs was that small amounts of oxygen gas, produced by photosynthesis, allowed BIFs to begin forming more than 3 billion years ago. The abrupt disappearance of BIFs around 1.8 billion years ago probably marked the time when oxygen gas became too abundant to allow dissolved iron to be transported in the oceans.
Banded Iron Formation
Source is unknown

It is interesting to note that BIFs reappeared briefly in a few places around 700 millionyears ago,during a period of extreme glaciation when evidence suggests that Earth’s oceans were entirely covered with sea ice. This would have essentially prevented the oceans from interacting with the atmosphere, limiting the supply of oxygen gas in the water and again allowing dissolved iron to be transported throughout the oceans. When the sea ice melted, the presence of oxygen would have again allowed the iron to precipitate.

References:

1. Misra, K. (1999). Understanding Mineral Deposits Springer.
2. 
Cloud, P. E. (1968). Atmospheric and hydrospheric evolution on the primitive Earth both secular accretion and biological and geochemical processes have affected Earth’s volatile envelope. Science, 160(3829), 729–736.
3. 
James,H.L. (1983). Distribution of banded iron-formation in space and time. Developments in Precambrian Geology, 6, 471–490.

Sunday, January 8, 2017

Siccar Point - the world's most important geological site and the birthplace of modern geology


Siccar Point is world-famous as the most important unconformity described by James Hutton (1726-1797) in support of his world-changing ideas on the origin and age of the Earth.

James Hutton unconformity with annotations - Siccar Point 



In 1788, James Hutton first discovered Siccar Point, and understood its significance. It is by far the most spectacular of several unconformities that he discovered in Scotland, and very important in helping Hutton to explain his ideas about the processes of the Earth.At Siccar Point, gently sloping strata of 370-million-year-old Famennian Late Devonian Old Red Sandstone and a basal layer of conglomerate overlie near vertical layers of 435-million-year-old lower Silurian Llandovery Epoch greywacke, with an interval of around 65 million years.
Standing on the angular unconformity at Siccar Point (click to enlarge). Photo: Chris Rowan, 2009
As above, with annotations. Photo: Chris Rowan, 2009





Hutton used Siccar Point to demonstrate the cycle of deposition, folding, erosion and further deposition that the unconformity represents. He understood the implication of unconformities in the evidence that they provided for the enormity of geological time and the antiquity of planet Earth, in contrast to the biblical teaching of the creation of the Earth. 

   
How the unconformity at Siccar Point formed.



At this range, it is easy to spot that the contact between the two units is sharp, but it is not completely flat. Furthermore, the lowest part of the overlying Old Red Sandstone contains fragments of rock that are considerably larger than sand; some are at least as large as your fist, and many of the fragments in this basal conglomerate are bits of the underlying Silurian greywacke. These are all signs that the greywackes were exposed at the surface, being eroded, for a considerable period of time before the Old Red Sandstone was laid down on top of them.
The irregular topography and basal conglomerate show that this is an erosional contact. Photo: Chris Rowan, 2009

The Siccar Point which is a rocky promontory in the county of Berwickshire on the east coast of Scotland.