Tag Archives: academic

All the academic papers I write.

Paleobiological Hierarchy

This page is best viewed in desktop mode. If you are using a mobile device, you can switch to desktop site using the switch link at the bottom of the page. Additional tools are available under Geology 491 – Paleobiology and the identification steps chart here. For more in-depth detailed information on how we classify the following fossils, please read, Classification of Fossils.

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I am unable to post pictures of lab samples. As such please submit your pictures to this page using server – at – sanuja.net email. I am willing to provide credits for your work! Just let me know if you would like to see your name on the site.

Kingdoms (largest divisions)

  • Bacteria
  • Protista
  • Animalia
  • Plantae
  • Fungi

Hierarchy

Note: The classifications used by the University of Calgary may differ from the materials on Wikipedia and other sources. This list is NOT specific to UofC classes such as 391/491. However, this may be used for reducing confusion.

You may find this chart of fossils based on their age useful. You may download them in image format and PDF format. Go save as for download.

Kingdom Animalia

  • Phylum Porifera
    • Class Stromatoporata
      • Genus Stromatoporoids (figure)
    • Phylum Archaeocyatha
    • Phylum Cnidaria
      • Class Anthozoa
        • Sub Class Zoantharia
          • Order Tabulata OrdovicianPermian
            • Genus Catenipora (image1 | image2 | image3 | figure) OrdovicianSilurian
              Chain coral; looks like links on a chain. The cross sectional view is usually have flat lines.
            • Genus Favosites (image1 | image2 | figure) OrdovicianDevonian
              Not to be confused with G: Lithostrotion and G: Hexagonaria. Honeycomb coral; closely packed polygonal and tubular structures. The center of each polygon has a slight depression while the longitudinal sides should have tiny “holes”.
            • Genus Heliolites (figure) SilurianDevonian
              Tubular structures. The cop view will most likely seen as somewhat circular “dots” (but they are actually shaped like flowers”).
            • Genus Syringopora (image1 | image2 | image3 | figure) SilurianPennsylvanian
              Small tubes often in mm in diameter. Often braches and looks like “worms”, “spaghetti” or “string of poop”. Highly concave (saggy) tabulae can be observed on thin section.
          • Order Rugosa OrdovicianPermian
            • Genus Heliophyllum (image1 | image2 | image3 | figure) Lower – Mid Devonian
              If the sample is a complete one, the external shape is look like a “horn”. The inside of structures should have striations which may appear as a floor like from the top cross sectional view.
            • Genus Lithostrotion (image1 | image2 | image3 | figure) MississippianPennsylvanian = Carboniferous
              Not to be confused with G: Favosites and G: Hexagonaria. They looks very similar due to polygonal shape. However, this is NOT closely (“tightly”) packed compared to G: Favosites. They also usually have 2-3 rows of dissepiments and have domed (curved) the tabulae (better to observe on thin section).
            • Genus Hexagonaria (image1 | image2 | image3 | image4) Devonian
              6-8 rows of dissepiments is a unique feature (slide or thin section is better for observation). Colonial life form with flat tabulae.
          • Order Scleractinia (image | figure) TriassicHolocene = Modern day
            Top view may looks like a mafia cut out human brain. But individually they should look like “pellets” of hamster poop. They add the septas in cycles in which each cycle consist of “in-between” additions. For example, if I am a Scleractinia type guy, I would add 6 first then, 6 + 6 + 12 + 12 + 24 + …
    • Phylum Brachiopoda
      • Class Inarticulata (Lingulata)
        • Order Lingulida
            • Genus Lingula (image1 | image2 | image3 | figure) OrdovicianHolocene
              Spatulate Valves with pedicle are placed between the two shells. Should be able to observe elliptical growth lines extending longitudinally on the surface of the shell.
      • Class Articulata
        • Order Terebratulida (image1 | image2 | figure) DevonianHolocene
          Biconvex shape and has large circular/semi-circular pedicle opening. Curved hingeline (look at the side view). The pedicle itself is often not preserved in the fossil record.
          • Genus Oleneothyris (image)
            Note the zig-zag commissure.
        • Order Spiriferida
            • Genus Atrypa (image | figure) SilurianDevonian
            • Genus Cyrtina () SilurianPermian
            • Genus Mucrospirifer (figure) Mid Devonian
              A distinct straight hinge line with a very large delthyrium (triangular shape in the middle). Biconvex shells with very well defined costae. Note this is used in labs as an example for Order Spiriferida.
            • Genus Paraspirifer () Lower – Mid Devonian
        • Order Orthida
        • Order Pentamerida
        • Order Rhynchonellida
        • Order Strophomenida
          • Sub Order Strophomenioina
          • Sub Order Productina
            • Genus Dictyoclostus (image | figure) Mississippian
              Spines (spike like). Chubby fat guy.
    • Phylum Bryozoa
      • Order Cyclostomata
      • Order Cheilostomata
      • Order Fenestrata
        • Genus Fenestella (image) OrdovicianPermian
        • Genus Archimedes (image1 | image2) MississippianPermian
          Screw like zooarium.
      • Order Trepostomata
        • Genus Hallopora (image1 | image2) OrdovicianDevonian
        • Genus Prasopora () Ordovician
    • Phylum Helmichordata
      • Class Graptolithina
        • Order Denoroidea
          • Genus Rhabdinopora (image | figure) Upper Cambrian – Lower Carboniferous
        • Order Graptoloidea
          • Genus Teragraptus (image) Lower Ordovician
            Also can be found in horizontal type in which it the organism looks like a cross/crossing branches. Uniserial variety.
          • Genus Phyllograptus () Lower Ordovician
          • Genus Didymograptus (image) Lower – Upper Ordovician
          • Genus Climacograptus (image | figure) Lower Ordovician
          • Genus Orthograptus (figure) Upper OrdovicianLower Silurian
          • Genus Monograptus (image) Lower SilurianLower Devonian
            Found in both straight and spiral formations.
          • Genus Cyrtograptus (image1 | image2 | figure) Mid Silurian
    • Phylum Chordata (Species Vertebrata (Cranrata))
      • Class Conodonta
        • Genus Streptognathodus (image) Lower PennsylvanianLower Permian
        • Genus Neogondolella () PermianTriassic
        • Genus Polygnathus (image) Lower DevonianLower Mississippian
        • Genus Palmatolepis (image) Upper Devonian
    • Phylum Arthropoda
      • Class Crustacea
        • Sub Class Ostracoda
      • Class Trilobita
        • Order Agnostida
        • Order Phacopida
          • Genus Calymene (figure) Lower SilurianMid Devonian
          • Genus Phacops () SilurianDevonian
        • Order Redlichiida
          • Genus Olenellus (figure) Lower Cambrian
        • Order Ptychoparida
          • Genus Trinucleus (figure) Ordovician
          • Genus Isotelus (figure) Mid – Upper Ordovician
        • Order Proetida (not on exams?)
        • Order Corynexochida (not on exams?)
      • Class Chelicerata
          • Genus Eurypterus
    • Phylum Mollusca
      • Class Gastropoda
        • Genus Bellerophon () OrdovicianTriassic
          T = 0 with involute planispiral coiling. Often find with ribs but with no sutures.
        • Genus Maclurites () Ordovician
          Low T, but not zero. With exceptions to few, almost always found as an internal mold. No sutures and it is trochospiral.
        • Genus Turritella () OligoceneHolocene
          Very very high T and therefore have an elongation along the trochospiral coiling. Dexutual coil.
      • Class Polyplacophora
      • Class Bivalvia
        • Genus Trigonia (figure) TriassicCretaceous
          Schizodont dentition. Curved hingeline. However, you may find fossils without the curved edges due to preservation conditions.
        • Genus Inoceramus (figure) JurassicCretaceous
          Very strong rugae.
        • Genus Mya (figure) OligoceneHolocene
          Spoon-shaped chondrophore.
        • Genus Mercenaria OligoceneHolocene
          Looks very similar to Genus Mya, but lacks the spoon-shaped chondrophore.
        • Genus Exogyra (figure) JurassicCretaceous
          Trochospirak with high translation (coiling out).
        • Genus Gryphaea (figure)
          Similar to Genus Exogyra but it is planispiral hence it curves inwards (“devil’s finger”).
        • Genus Pecten (figure) EoceneHolocene
          Very strong ribs. Auricles (wing-shaped) on both sides for swimming. The larger aurticle points to the anterior direction.
        • Genus Rudistid () Cretaceous
          Not to be confused with corals or bryozoans. Small lids which covers to tops are often missing from lab samples.
      • Class Scaphopoda
      • Class Cephalopoda
        • Sub Class Nautiloidea
          • Genus Euterphoceras
          • Genus Nautilus (figure) OligoceneHolocene
        • Sub Class Actinoceratoidea
        • Sub Class Endoceratoidea
        • Sub Class Bactritoidea
          • Genus Bactrites () DevonianPermian
        • Sub Class Ammonoidea
          • Order Goniatitida
            • Genus Tornoceras () Devonian
            • Genus Goniatites () Mississippian
          • Order Ceratitida
            • Genus Ceratites () Mid Triassic
          • Order Ammonitida
            • Genus Dactylioceras () Lower Jurassic
            • Genus Harpoceras () Lower Jurassic
            • Genus Baculites () Upper Cretaceous
            • Genus Scaphites () Upper Cretaceous
        • Sub Class Coleoidea
          • Genus Belemnites (figure) JurassicCretaceous
    • Phylum Echinodermata
      • Class Asteroidea
        • Genus “Starfish” (figure)
          Five fold ( pentameral) symmetry. A good example of a living fossil. Well defined body wall and sometimes the central five side disc may be observed in the center.
      • Class Blastoidea
        • Genus Pentremites (figure) MississippianPennsylvanian = Carboniferous
          Small structures that looks like wrapping around a small ball. The five fold ( pentameral) body is often covered in a “cap” shaped external structure.
      • Class Crinoidea
      • Class Echinoidea
        • Genus Micraster (figure) Upper Cretaceous
        • Genus Dendraster (figure) PlioceneHolocene
          Dome (“circular”) shaped overall structure. Flower like appearance on the surface. Very good example of five-fold radial symmetry on the cross sectional body.
      • Class Edrioasteroid
        • Genus Isorophus () Mid – Upper Ordovician
      • Class Erhombifera (“ctriuds”)
        • Genus Strobilocystites () Mid – Upper Devonian
          Looks like a pellet of poop. Not to be confused with Genus Pentremites. Small dotted “ball” like structures within the five fold star like physical frame.

    Kingdom Protista

    • Phylum Chrysophyta
      • Sub Class Rhizopoda
        • Order Foraminiferida
            • Genus Textularia () PennsylvanianPlioceneHolocene
            • Genus Globorotalia () PlioceneHolocene
            • Genus Globigerina () PlioceneHolocene
          • Sub Order Fusulinina
            • Genus Schwagerinid wall () Upper PennsylvanianMid Permian




    Why won’t you publish digital photos of the lab samples? Unfortunately I am a member of the Faulty of Science since June 2013. As a result, I am not allow to publish images of lab samples on my site. However, if you would like to have images here, please email your images to me so I can post them on this site. Sorry for the inconvenience.

    How does this colour scheme work? Oh well… like this
    Quaternary
    Holocene = Modern day
    Pleistocene
    Pliocene
    Miocene
    Oligocene
    Eocene
    Paleocene
    Neogene
    Paleogene
    Cretaceous
    Jurasic
    Triassic
    Permian
    Pennsylvanian
    Mississippian
    Devonian
    Silurian
    Ordovician
    Cambrian

    Thank You

    Felicia MacMurchy, Kathleen Nester, Pulkit Sabharwal and Laura A McCowan, University of Calgary (Undergraduate Students)


    How to use a Brunton Compass

    It is essential for a Earth Scientist to be skilled at using the tools of the trade. From day one, students are trained to use the Brunton Compass, a highly popular measuring tool. I am very proud to say it was first designed and developed by a Canadian Geologist, David W. Brunton. If properly used it is a great tool for taking precise geological measurements within few degrees or meters of accuracy.

    Skip Background Jargon

    Parts of the Unit

    Initially the compass was made out of metals which makes the unit very expensive. Recently the Brunton company produce two different versions of their models; one with the original metal body and another with high density plastic. I personally prefer the original unit because I like the weight and feel of it. However, both versions will provide the same results and both versions comes with exact same layout.

    Before start using anything, we need to learn the layout and features of the device. The compass has a hexagonal shape to it’s outside perimeter creating flat perfectly straight surfaces. This is not for aesthetic appeal. The flat surfaces, specially on each side, provide the support for measuring angles of inclines and angles of strike of Geologic features. The base casing has an arm mounted to the body for directional measurements. Even the cover (lid) of the unit has a mirror which function as a sight taking tool. Everything on the Brunton Compass is a tool.

    Features of the Pocket Transit Compass
    Features of the Pocket Transit Compass

    Above image is a picture of typical Brunton Pocket Transit Compass model used by universities and professionals. A list of key components on the base casing can be summarized;

    A – Long Level – Use for taking azimuth measurements of strike.

    B – Circular Level – Use for taking angle measurements of dip.

    C – Iron Needle – Points to magnetic North and it is damped using the magnet below the pivot point. But the bearing can be adjusted accordingly by rotating the declination zero pin.

    D – 360-degree Graduated Circle – Use for azimuth readings that are accurate to half of a degree.

    E – 90-degree Dip Circle – Use for measuring dip using the long level on the vernier.

    F – Needle Pin – Helps to lock the needle in place in order to take a reading.

    G – Vernier – The vernier is used for inclination measurements with an accuracy to 30 minutes.

    H – Rare Earth Magnet – A cast NdFe magnet which allow the iron needle to seek North accurately and quickly. It also reduces the magnetic interferences from the nearby environment.

    J – Declination Zero Pin – An arm behind the compass is used to move the pin. Using tabulated data on magnetic declination, the degree of correction is set.

    Usage

    Here is an example of taking a strike on an inclined surface. Taking dip measurement is not shown here, but it is done by laying the Brunton Compass on the side along the dipping surface. By moving the vernier and long level, you can measure the dip.

    Taking a strike on an inclined surface.
    Taking a strike on an inclined surface. Click on image for original.

    Silicate Mineral Structures

    Click on the image for larger high resolution file.

    Dark blue is Silicate Tetrahedra, green is bonds and the light blue is sodium.

    Olivine - Isolated Tetrahedra
    Olivine – Isolated Tetrahedra

    The isolated tetrahedra is a group of silicates in which the crystal structures have no shared oxygen between them. Therefore minerals like Olivine and Garnet are held together by the attaraction force between silica tetrahedra and the surrounding cat ions. This is the least polymerized type.

    Clinopyroxene - Single Chain - Pyroxene Group
    Clinopyroxene – Single Chain – Pyroxene Group
    Atomic model of Clinopyroxene
    Atomic model of Clinopyroxene

    Single chain silicates have links between the silicate tetrahedras by sharing two oxygen atoms between two of them. Pyroxene is the most common group in this category.

    Actinolite - Double Chain - Amphibole Group
    Actinolite – Double Chain – Amphibole Group

    Double chain silicates shares two or three oxygen atoms. You can look at these structures as two independent chain silicates bonding together because the fundamentally, they are two set of chains. Amphiole group is an example of such minerals.

    Biotite - Sheet - Mica Group
    Biotite – Sheet – Mica Group

    Sheet silicates form 2D silicate structures. All sheet silicates share exactly three oxygen atoms between silica tetradera. While sheet themselves are strong, in between the sheets different types of molecules can be fitted in. One for the example of this would be the water molecule in which a hydrous form of the mineral is formed. Micas such as biotite and muscovite are examples of such minerals.

    K-feldspar - Framework - Feldspar Group
    K-feldspar – Framework – Feldspar Group

    Framework silicates are the most polymerized version. The structure uses all four oxygen atoms in the silica tetrahedra to form bonds between them. Feldspars are the most common type of framework silicates.

    Improving spatial visualization skills

    There are thousands of research reports written on 2D and 3D thinking skills on the internet. You can read them all, but I do not believe absorbing those highly academic reports would make any difference for improving your ability in spatial visualization. The main message in all those reports is; the ability to understand 3D structures are very important to Science and Engineering students.

    Skip the Jargon

    If you were exposed to activities which force you to think in 3D, such as building blocks/Lego®, then you already have the basic knowledge on spatial visualization. Even if you were not familiar with such activities, as a Science undergraduate student, I am sure you have felt the pressure to think in 3D in some of your classes. I was extremely unconformable in my Structural Geology labs not because I do not understand the concepts in Geology, but I could not get my head wrap around the idea of having different views (interpretations) on a single structure. If you feel that you are “stuck” at thinking in 2D or 3D, do not give up because spatial visualization skills can be improved through 3D and 2D activities. One thing I have to make clear; I DO believe that spatial skills can be improved with experience, so it takes time.

    Why university students may find it hard…

    There are million reasons why, but some of the most common issues would be;

    • Prejudice negative attitude towards any subject that involves Math and Physics.
    • Coming in to Geology and assume it is more of an Art than a Science.
    • Underdeveloped critical thinking skills.
    • Preconceived notion about teaching styles of academic institutions.
    • Not putting enough time into the subject outside of the regular classes and labs.
    • Get it done attitude with no interest in learning the concepts.
    • Inability or inexperience in breaking down complex problems into smaller sections.
    • Learning or physical disabilities which hinders the ability to demonstrate full potential on exams.
    • Lack of guidance on how to improve critical thinking and spatial visualization skills.

    I am not going to address them all. I am not qualified to do so and it takes a lot of my time to do research using academic databases (they are so unlike simple Google Search!). Today I am going to take on the last point, the guidance on how improve critical thinking and spatial visualization skills.

    Math helps, but it depends…

    I had talked to a lot of students at University of Calgary who had enrolled for Winter 2013 academic session. They think the Structural Geology class is hard even before the labs were started. The overwhelming response was the fear of 3D spatial visualization. Some students just do not even want to give it a try while others, including myself, gave up after the first few tries.

    It should not be that hard considering some of us were able to score extremely high averages in Physics, Chemistry and Biology in high school (and the University). The problem I think is that we lacks the ability to translate our theoretical thinking into more practical visualization. For example, in the figure below, a current I flow through a straight wire has a magnetic field, B wrapped around the wire. But the magnetic field itself has a direction.

    Right Hand Rule in Physics
    Right Hand Rule in Electrics and Waves

    The term “Right Hand Rule” is used in numerous applications of science. In Geology, we use our Right Hand Rule (of different kind) to find the strike and dip directions of a feature.

    Right Hand Rule in Geology
    Right Hand Rule in Geology

    Here is the surprise! Even with some difficulty, most students would be able to understand the Right Hand Rule in Physics, but a large portion of the same group would struggle to understand the Right Hand Rule in Geology. The poor performance in our advance/intermediate Geology classes does not always reflect our abilities. Some Professors and TAs (Teachers Assistants; Graduate Students) told me that they cannot explain why we seems to be getting dumber as we progressed in our degree.

    I believe Mathematics and Physics are the foundation for any type of science. Regardless which specialization you choose, the skills you learn in those two subjects can make the difference between being a good Geology student and being a great one. If you are a high school student, please seriously consider taking all three sciences all the way to Grade 12.

    Pundits on childhood learning

    New studies shows that these type of skills are not improved due to student’s ability to do well in math and science, but rather the opposite. Children who are exposed to critical 3D and 2D thinking will most likely excel in Science and Engineering than those who did not 1. Scientists agree that special thinking, specially orientation, is a skill which obviously can be improved. But like languages, once the mold has been created it will be bit difficult to retrain the brain. This is I think it is so impotent for Kindergarten and Elementary school educational system to include 3D and 2D activities. Not only these activities could help the future instructors of these children, but also can spur their interest in science.

    In 2012, a company had created (by Debbie Sterling, an Engineer herself) a toy set for girls called Goldie Blox2. The primary goal was to introduce 3D spatial visualization skills to children so that when they grow up, these young women will be interested in Engineering. I do not have evidence on the effectiveness of the Goldie Blox, but considering all the other “pundits” observations on early development of spatial skills, I am sure it is (probably) would be a success.

    3D thinking for Geologists

    Each and every person have their own way of improving skills. What is common to all of us is the final goal; robust interpenetration of subsurface Geologic features using deductive reasoning. There are three major components to spatial visualization;

    Relations, Manipulation and Penetration
    Relations, Manipulation and Penetration 4

    • Spatial Relations; is the ability to mentally rotate an object on an axis3. Almost all Geologic features have undergone some form of rotation, even if it is as small as few degrees. I found most of the natural features have more than one rotational axis.
    • Spatial Manipulation; is the ability to mentally manipulate an image into variety of arrangements. The deformation history and mechanisms in Structural Geology is based on the deductive reasoning of spatial manipulation. A Geologist should be able to determine the unreformed state of materials based on the stress and strain indicators of the present state4.
    • Visual Penetrative Ability; is building a mental image of what is inside of an object using educated guesses and visible relationships. This is very important for Field Geologists. During my first field school I was forced to think inside the box when we analyzed the major folding event in Grotto Canyon in Canmore, AB. It is highly impractical for a Geologist to physically dig kilometers of hard rock and sediments to collect direct data even in small scale Geologic events5.

    Big picture

    All of the following figures (diagrams) were created using the web application developed by a University of Calgary Graduate Student6. Click on the image to view the original high resolution file.

    You can improve your 3D spatial visualization skills by breaking down the large Geologic problems in to small pieces. I used the following approach. You may modify it to fit your learning styles.

    1. Read and understand: The time you take to read the background of the Geologic feature / area in question depends on your current abilities in 3D thinking. Take your time to read as many materials as it needed even if it seems a waste of time (trust me, it is not a waste).

    2. Starting out: Do not jump into complex problems with multiple Geologic features. Instead choose a simple concept. Just because something is simple, it does not mean you won’t be exposed to the major components of spatial visualization. The following figures show a flat plain cutting across a 3D block.

    A plane (demonstrate a plainer feature)
    A plane (demonstrate a plainer feature)
    The perspective of the first figure (above) shows most of the plane that cut through the block. You should be able to see that, it is at an angle (045-degrees to the horizontal) even though you do not know the exact measure of it.

    A plane (demonstrate a plainer feature) in a different view
    A plane (demonstrate a plainer feature) in a different view
    This one is another perspective of the exact same figure. Now you can see the North arrow is pointing away from the screen. You should be able to notice that the North arrow, which is a straight line, is not parallel to any of the edges of the plain (assume the plain is a perfect undeformed square). What does / doesn’t that tell you?

    It tells you that the plain is not intersecting the block parallel to the North-South direction. In other words, it has a strike! To be exact, the strike is 160-degrees, but regardless of the exact value, you should be able to deduce it has a non-zero strike by just looking at it.

    What did we cover so far in this simple example? We covered spacial relation and penetration.

    3. Add Geologic layers: We can now replace the plain 3D block above with something more practice; a layered rock unit. For this example, it is still a perfect cube with perfectly horizontal layers. Can you visualize the layers in different orientations?

    Normal fault with layers (side view)
    Normal fault with layers (side view)
    Did you realize that this is a normal fault? How long it took you to deduce the conclusion (without reading the figure caption)? At least if you have realized that this is a type of fault, that means your brain had recognized the layers as flat and continuous and associated the “odd” change on the South face of the block as a fault! That is what I call robust interpenetration. Most of us should be able to know what this figure is showing in less than 30 seconds. This robust ability to interpret diagrams and associate it with theoretical Geology is actually a skill that you developed through your training. STOP and think about it. This is pretty cool right?

    4. Dipping with a fault: The Geologic layers are no longer horizontal. Yes, they are dipping, but do you notice anything special about them?

    Right lateral fault with dipping layers (side view)
    Right lateral fault with dipping layers (side view)
    Left lateral fault with layers (side view)
    Left lateral fault with layers (side view)
    In both figures above, you should be able to recognize the sense of movement. In addition, all the layers are dipping at the exact same angle in our 3D block (that’s what so special about them).

    5. Geologic manipulation: Finally now we have figures with somewhat complex deformations. They are all examples of anticlines, so to me they are not that complex at all.

    An anticline with layers (top view)
    An anticline with layers (top view)
    If you are in the first year Geology class, first look at this block diagram from top perspective. From the top (or map view), you can only get limited information on the Geology. We can deduce that there are different layers. We could not tell which way they are dipping nor assume the relative thicknesses. But if I was to guess, I would say the beds have different thicknesses (this is incorrect).

    This highlights a very important difficulty in 3D thinking. How do you know, your version of the story is right? The fact is, you do not. In the real world Geology, we use “quality of data assessments” to determine the probability of error. There are many different software like GeoScout, Golden Surfer, IHS Kingdom and many more to analyze the quality of data. While I love to talk about Computer Science side of Geology, I would leave that for another article (hint: it’s coming up!). The take home message is that quality of data is more impotent in Geology than the quantity of data.

    The layer thickness is almost the same, if not at least the volume of each layer had not changed. The following side view of the exact same block shows an anticline. The block had been subjected to differential stress. Can you deduce the hinge-line? Is it plunging in any direction?

    An anticline with layers (side view)
    An anticline with layers (side view)
    The answer is yes and no. We can safely say (not prefect) the hinge line is probably in the North-South direction. We can also say it is not plunging since we do not see the beds dipping along the North – South direction (assume there is no unnoticeable small plunge).

    The following figure is an example of a plunging anticline. It is recognizable from the North-ward dipping beds parallel to the hinge line (or zone).

    A plunging anticline with layers (side view)
    A plunging anticline with layers (side view)

    By simply manipulating the spatial relations, we were able to significantly improve our quality of data (hence improving the spatial visualization as well).

    FOLDS IN DEPTH
    I wrote a separate article on the 3D Geometry of Folds with much more vigorous details on fold anatomy. I recommend reading it for all Geology students.

    6. Putting all three together: This is an advanced example that will test your abilities in all three major components to spatial visualization. The following image has two views combined as a single figure. On the left hand side, the 3D block image and on the right hand side, a map view of the same area. It is in a valley (but no contour lines are shown), it has two major folding events, two faults and non-zero strikes and dips for all the Geologic features.

    Complex structures; a valley with a coal seam and fault. Borehole is indicated with the vertical tube.
    Complex structures; a valley with a coal seam and fault. Borehole is indicated with the vertical tube.
    The black layer is a coal seam and the tube on the left image indicates a proposed borehole for coal exploration. Now if you add vital elevation contour lines and may be structural contour lines, we are in heaven! Geology Rocks!

    ADDITIONAL TIP
    Now you have the background knowledge, do not forget to try out Visible Geology. There is a lot more to spatial visualization in Geology than what I talked about there. For example, how about cross sections?

    Cross section of a ridge.
    Cross section of a ridge.

    References

    1. Toddler Spatial Knowledge Boosts Understanding of Numbers

    2. Goldie Blox

    3. Shepard and Cooper, 1982 AND Shepard and Metzler, 1970

    4. Guay (1976) and Ekstrom et al. (1976)

    5. Kali and Orion, 1996

    6. Visible Geology

    How to read Geological Maps

    For someone who is new to Geology, reading highly technical maps could be a challenge. I remember even I had trouble reading data off of maps when I was in first year Geology class. It is nothing to be shamed of because I know even the most seasoned Geologists who read their maps wrong. But the difference between a skilled Geologist and a lay person is that a Geologist would be able to find his/her own mistake. This article will introduce you to the most fundamental aspects of Geologic maps.

    Direction

    True North Indicator.
    True North Indicator.
    Most maps are published with respect to true North. When working in the field, the compass will read the magnetic North. To correct this error, you should find the magnetic declination for the region either using the provided data on the side of the map or by extracting the information from services such as USGS official website. To take measurements off of a map, use a navigational protractor to find the angle between the feature and the North (angles are always measured clockwise). In the field, bearing of a feature is always read from the North and should be redecorated with not just the angle, but also the location, date and time. Make sure that you have adjusted your compass declination arm with the correct angle of declination before taking any measurements.

    Scale and Contour Interval

    Depending on the type of map, the scale may be given in several different units. This is because of the conventions we use today have been evolved slowly depending on the task. For example, most Geological maps will include a feet scale along with miles or kilometers. This will avoid the issue of having elevation and structural contours (which usually given in feet) in one unit and the map scale in another.

    Scale in miles an km
    Scale in miles an km

    There are maps that use only one type of measurements. However, rarely you would come across a map that uses meters for contour over feet. While it does not matter which type you use, I recommend using feet since it will reduce the conversion errors in the long run.
    A Geological map with contour lines.
    A Geological map with contour lines.

    Contour lines are always changes at a set interval, but not with a set distance.

    Formations and Features

    Finally, recognize the different formations and use the contacts between them to calculate strike and dip. (The key for the colour coding should be printed on the map itself.) It is a common practice to use a Navigational Protractor for measurements. If you have to draw structure contours, use two triangles to move from one line to the next. This will keep all your lines parallel to each other.

    Navigational Protractor
    Navigational Protractor

    Some maps are published with specific information on Geology. This type of maps are based on extensive research than general geological maps. For example, a structural map of a small area could contain several faults and complex mountains. While these features will also show up on a regular geologic map, structural Geologist may find it difficult to work without having the access to specific details.

    A repeated GPS based map of Aegean region between 1993 and 1998.
    A repeated GPS based map of Aegean region between 1993 and 1998. The symbols are used to indicate the rotational motion of blocks.(1)

    Symbols and Conventions

    You may be surprised to hear that Scientists have not come to a complete agreement on what symbols we should use for what purpose. We have been using so many different symbols or variations of symbols, that sometimes reading data could be difficult. My approach to this problem is to first read all the available data on the map itself. Date of publish, the publisher, the year of publish and the location often contributes to how it is printed. For example, the following two figures shows few variations in symbols for folds.

    Some of the common symbols used for folds.
    Some of the common symbols used for folds(2)
    Fold block separation symbols.
    Fold block separation symbols(2)

    Tips

    The geometry of the elevation changes are often complicated, thus the patterns such as space between contour lines and their shapes can be used to identify key features. For example, the rule of V states, if several lines are pointing to one direction in the shape of a “V”, then it is most likely a valley or a fold. If it is a valley, the dip is in opposite to the point on the V. In other words, upstream is in the direction of the tip of the V.

    Learn more

    USGS – How to use a Compass

    References

    1. Earth and Planetary Sciences Letters, v.172, Cocard, M. andothers, Newcon-strain tsonthe rapid crustal motion of the Aegean region: recent results inferred from GPS measurements(19931998) across the West Hellenic Arc, Greece, p.3947