Basics of Field Geology

Basics of Field Geology Rex A. Crouch

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Copyright 2008 by Rex A. Crouch

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Preface This text addresses the basics of field geology for the amateur geologist and prospector with the assumption that the reader has an introduction to earth systems, mineralogy, petrology, and structural geology. Observation and data collecting, using the transit compass, plotting features on a map, and the geologic report are addressed herein.

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Chapter 1 - Observing and Collecting Data The purpose of field geology Planning the field project Taking field notes Collecting hand samples Chapter 2 - Using a Transit Compass and Global Positioning System The transit compass Taking a bearing Strike and dip Global Positioning System Chapter 3 - Plotting Geologic Features on a Map Color standardization Symbol standardization Preparation The field map The mapping story Chapter 4 - The Geologic Report Purpose of geologic reports Report format Target audience

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Chapter 1 - Observing and Collecting Data Purpose of Field Geology. Field studies are the main method of obtaining geologic data. Field studies should have a purpose, even if it be strictly academic. The study may be as simple as a single outcrop of interest or an open pit quarry. These simple studies may include a sketch, some digital photos, GPS coordinates, making notes on relations between rocks, and/or collecting some hand samples. Other field studies may be complex requiring extensive time in the field utilizing systematic sampling methods of rocks, soil, and even water with detailed mapping in computer applications.

be found by geologists with their boots on the ground, in the field, mapping an area. Some ore deposits may be found with airborne geophysics but in reality, few are, it is the geologist in the field that makes the discovery. Ultimately, maps convey more than words ever will. Mapping comes down to the observations at the individual outcrops as being the fundamental principle of field geology. The observation and an interpretation is made, a hypothesis is developed, and tested by any means available. The individual outcrop will be the most rudimentary aspect of mapping. As the map develops complex relations are revealed. Complex relations may occur when multiple processes act simultaneously or through overprinting of multiple geologic events. Sometimes geologic features may be so complex that no distinct conclusion can be

Geologic mapping is the backbone of the field study and is frequently referred to as field geology. Mapping finds relations between rocks and other geologic interests. Despite our advanced technology many geologic features of importance such as folds and faults can only 5

found. Upheaval Dome in Canyonlands National Park is believed to be a collapsed salt dome by one camp of geologists and a meteorite impact site by

another. Other complex features are understood only when detailed field mapping has been conducted and interpreted.

Planning the Field Geology Project. Field projects have three phases: Planning/Research Observing/Mapping/Collecting Reporting

While each phase leads into the next, the writing of the report should actually begin during the planning and research phase. Planning/Research – This is as critical as the other two phases. Here, the scope of the project must be determined. One specific location is identified and purpose for being there is clearly stated. Without a place and a purpose the geologist becomes a free-range chicken. The research is also critical. A lot of the work may have already been completed and available through aggressive research; some field mapping may have

already been done and drill cores with chemical assays may be available. Judging the data recovered from research may be difficult. Many brilliant professors and research teams have been wrong on multiple occasions. Sometimes the original researcher simply wasn’t objective. The world was considered flat for a longtime, then considered round, and now we know that was wrong too. Over time techniques and 6

technology change and allow geologists to see datum under a different light. Be prepared to accept the researched data and test it to ensure its validity.

boulders setting on top of mafic bedrock, valleys or flowing water bodies across the strike. The primary school of thought is to map what is in-place or geologic bodies that are part of the bedrock but what about that huge granite boulder setting on top of mafic bedrock. Some geologists will annotate this boulder on their maps as they may encounter the granite bedrock it originated from 10s or 100s of kilometers away—this is a great example of glacial activity.

Observing/Mapping/Collecting – This phase is what geologists call “Boots on the ground.” Outcrops are observed. The rock type is identified. Distinctive items such as crystals or fossils are scrutinized. Besides the fine details, geologists look for the obvious such as slicken slides, big granite

Taking Field Notes. As geologic features are encounter they should be annotate in the notebook. The geologist makes the notes at the location of interest to ensure all data is properly collected. The field notes complement the geologic map and will serve as the basis for writing the report. Good notes are clear and do not have unexplained abbreviations. Sloppy abbreviated shorthand of a geologist who made critical

observations decades could leave the work done as useless. The notes a geologists takes may be instrumental in the development of a current project or a project years or even decades later. Geologists develop systematic approaches for taking notes ensuring all of the datum are collected at each outcrop or geologic feature encountered. An example of topics to cover: 7

Numeric that correlates the notes to the features drawn on the map Name of formation – if known Specific location Characteristics such as thickness Name of rock Description of rock – the description should also be systematic addressing rock and mineral properties o Color o Type (igneous/sedimentary/metamorphic) o Texture o Foliation (as appropriate) o Folds (as appropriate) o Cleavage (as appropriate) o Luster o Hardness o Streak (as appropriate) o Magnetics (as appropriate) o Luminance (as appropriate) A sketch of the geologic feature may be made or a digital photo taken. In either case, ensure that a ruler is included in the sketch or photograph and annotate in the notes the orientation of the image. Photographs using coins or local items for scale from the country where the photo was taken lose meaning outside of that country and locally even after time; pesos change size every year. A ruler is a good scale because a centimeter is a centimeter around the world. A small insert map may also be prudent if macro view would add value to the description. If a hand sample is taken ensure the number identifying the sample is annotated in the notes.

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Collecting Hand Samples. The reason for collecting hand samples is to give the geologists the opportunity to further examine the rock at camp or in a lab. Much more can be discerned with Petrographic polarizing microscope and even

more may be learned X-ray crystallography and geochemistry testing. Standardization of hand sample collecting should be established prior to going to field—subjects to standardize are:

Numbering method - When multiple geologists are involved a scheme to identify the collecting geologist is also of importance The rough size of the collected sample That is represents the formation as a whole Marking orientation

Numbering method – The numbering method for hand samples should correspond to the notes as closely as possible and have a scheme for relating the rocks to the study area. Finding boxes of rocks in the lab each labeled 1, 2, 3 will lack meaning. If the samples are collected at “Example Creek” a possible numbering scheme would be EC 2d. The letter “d” may represent the 4th sample,

collected at outcrop “2”, at “Example Creek.” The number should be annotated with a permanent marker. Whiteout can be used on dark colored rocks with the number placed on the whiteout. Rocks with phaneritic textures may simply need to be bagged; a number is later written on a label and glued to the rock.

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Size – Rocks with homogenous matrices may be fist sized. Rocks with large crystals or coarse grains may warrant a larger sample.

of the crystals limestone contains.

that

the

Marking orientation – Rocks having folds and foliations need to have to have their orientation annotated. Clearly mark which side is up. If this is difficult mark a band around the rock showing the level line and annotate one side as “TOP” and indicate the bearing from when the rock fit into the outcrop

Representing the formation – Taking one large pyrite crystal would poorly represent the limestone formation that contained a few crystals. In this case taking a hand sample of limestone would be prudent and of course take a representation

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Chapter 2 - Using the Transit Compass and Global Position System Geology curriculums typically contain to two summer field courses but these courses have seen changes through the years. One of these courses was dedicated to surveying and may have included the use of an alidade and the second field course was geology. The

surveying course has been removed from most geology curriculums which was a tool geologists could use to locate themselves. This handbook will introduce the Global Positioning System or GPS and how to employ it in concert with a transit compass.

Transit Compass. A transit compass includes a magnetic compass, clinometers (Long Level), and hand level (Round Level) in one package. The transit compass most widely used by geologists today is called the Brunton. The Brunton we know and use was

designed by Canadian geologist D.W. Brunton in the early 1890’s. Although the Brunton Company makes a variety of equipment, the word Brunton is widely accepted to mean transit compass.

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The various parts of the Brunton are depicted below.

1. 2. 3. 4. 5.

Bearing Needle Graduated Circle Zero Pin Large Sight with Peep Sight Small Sight

6. 7. 8. 9. 10. 11.

Mirror Long Level Adjusting Screw Lift Pin Vernier Round Level

The Graduated Circle may be moved east or west by turning the Adjusting Screw and is observed using the Zero Pin. Because true north and magnetic north are not in the same location, the compass will have to be adjusted to point toward true north; this will change from location to location. The field maps used will have a section called “Declination”. The declination states how many degrees east or

Depressing the Lift Pin stops the motion of the compass needle and when the box is closed the Lift Pin protects the needle. The Round Level is used to level the compass when taking bearings. The Long Level is used to take clinometers (dip angle) readings—the lever on the back of the compass manipulates the Long Level. The dip angle reading is made on the Vernier.

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west the compass will point away from true north. Turn the Adjusting Screw until the graduated circle has corresponds to the declination on the map. In Maine the compass will have to be adjusted about 18 degree west whereas in Washington the compass will have to be adjusted about 18 east. Along the Mississippi River there may be no need to adjust the compass.

must remember that the report will never be greater than 90 degrees; subsequently a bearing of 91 degrees will be reported as S89E. The east and west indicators on the compass seem to be reversed however this orientation assists in reporting in the correct format. There are many methods for taking a bearing. The transit compass may be mounted on a tripod or alidade mount for the greatest accuracy. In rugged terrain the tripods can be very cumbersome. The compass to cheek method using the peep sights is a fast method for taking a bearing.

Taking a Bearing. A bearing is the direction the compass needle is pointing. In geology there is a specific format for reporting a compass bearing—this report will never be greater than 90 degrees. As an example, if the bearing reads 35 degrees then the report would be annotated as N35E. If the bearing was 91 degrees we

This handbook recommends the waist level measurements technique.

Ensure there are no metallic objects such as belt buckles that may affect the compass needle Open the compass housing to about the 2/3 point Hold the compass at waist level 13

While looking down at the compass, sight the objective in the mirror, ensure the system is level using the round level Depress the Lift Pin locking the needle in place Observe and record the bearing

In the following example:

There are four basic principles of geology being: Principle of faunal succession – This principle is based on the observation that fossils succeed each other in a vertical manner Principle of cross-cutting relationships – Rocks that have cut through other rocks such as dikes or sills are younger than the surrounding rock Principle of lateral continuity – Sedimentary rocks extend laterally in all directions Principle of original horizontality – Sediments that form sedimentary rock are deposited horizontally

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This final principle brings us to strike and dip. Geologic activities rarely leave rock in a horizontal position and it is

critical for us to measure the strike and dip to discern what has happened at the site as well as the region.

Strike and Dip. Measuring the strike and dip of a geologic feature uses all three functions of the transit compass being the magnetic needle, Round Level, and Long Level.

The dip angle will always be orthogonal to the strike. A trick for finding the strike is to pour some water on the rock. The water will flow in the direction of the dip and the strike is orthogonal as stated.

The strike is found by placing the edge of the compass against the inclined rock and adjusting the compass position until the round level is center. With the edge of the compass flush to the rock and the round level center observe and record the bearing. For this example the bearing is N35E.

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The dip is found by placing the compass flat against the rock orthogonal to the strike. Adjust the lever on the back of the compass until the Long Level is flat. Observe and record the measurement seen on the Vernier. For this example it is 45 degrees.

This may also be annotated on a geologic map with a long line pointing toward N35E and an orthogonal line pointing in the direction of dip with the dip angle annotated adjacent to the symbol.

This may be written as N35E 45

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Global Positioning System. The GPS is a ground based receiver which uses a series of satellite signals and triangulates itself based on these signals. There are two different varieties of GPS units being the commercial and the profession version. The commercial version is typically accurate to within 4 – 9 meters on the X Y axis and about 15 meters on the Z axis. The professional version is accurate to within a meter on the X, Y, and Z axis. This accuracy is even further refined with special antennas and base units.

Whether using the commercial or professional version of a GPS there are two measuring schemes- These are Latitude and Longitude or Universal Transverse Mercator UTM. Latitude and Longitude uses degrees, minutes, and seconds, and is a projection of grid lines on sphere. This results in measurements being made with degrees, minutes, and seconds. The UTM system was designed by the military and is a flat grid based system. A flat system becomes distorted in the Polar Regions but warfare in the arctic is unlikely. The system of measurement uses zones ranging from 01 to 60 horizontally and letters vertically. The letters “I” and “O” were omitted as they could be confused with numbers.

For most field geology applications a commercial unit is adequate. When accuracy becomes critical is when gravity measurements will be taken. Accurate gravity measurements are dependent upon elevation making the professional version of the GPS essential.

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All GPS units have similar features allowing the user to select UTM or Latitude and Longitude. UTM is used for most applications today to including modern geology tasks. Most computer applications and even maps use UTM. When selecting UTM there are two additional selections to be made being the database and the spheroid. Because the earth does not remain stationary nor is it a perfect sphere there are different reference frames and spheroid models in use. The World Geodetic System (WGS) allows us to define the Earth’s reference frame. As we learn more about the earth we update

the reference frame and spheroid models. Select the most current WGS when setting up the GPS unit. The earth is not even a perfect oval; it has varying degrees of roundness at different locations. The spheroid of Earth changes locally. In the United States we use North American Datum or NAD 83. A word of caution, because there are so many different coordinate systems available from Range and Township, Latitude and Longitude, State Plane, and many variations in UTM dependent upon the age of the data and spheroid location, 18

geologists must ensure that any data or maps used have been converted into the same coordinate system. The difference between UTM NAD 27 and UTM NAD 83 may be on the order of 10s of meters dependent upon location. A failure to ensure the correct spheroid is in used compounded by a commercial GPS unit’s potential error of 4 – 9 meters

could become distance.

a

significant

Another important function of most GPS units is the ability to establish Way Marks. Geologists mark important locations on their GPS units and enter detailed data about the location. Good geologists also ensure that data and location of any observation is entered into their geology notes.

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Chapter 3 - Plotting Geologic Features on a Map trails, and topography. The drawback is that it convolutes the data collected making the map difficult to read. This handbook recommends grid paper for mapping. Grid paper may also be found in a water resistant variety.

Color Standardization. Maps used in the field for documenting geologic features and referred to as base maps or geologic maps. Other map types may show drainage which are called planimetric maps. Culture maps show manmade features and topographic maps show contour.

To limit the size of the legend geologists use accepted geologic symbols and colors. The following represents the accepted color coding for rock ages as presented by the USGS:

Some people prefer to use topographic maps as their base map. As a benefit of this method, the user will have reference points such as roads,

Precambrian RGB 178/134/83 Archean RGB 153/173/172 Eoarchean RGB 128/144/144 Paleoarchean RGB 153/151/145 Mesoarchean RGB 203/205/200 Proterozoic RGB 204/216/145 Paleoproterozoic RGB 179/178/94 Mesoproterozoic RGB 221/194/136 Neoproterozoic RGB 202/165/149 Tonian RGB 203/164/108 Cryogenian RGB 220/171/170 NeoproterozoicIII RGB 234/216/188 Phanerozoic RGB 179/226/209 Paleozoic RGB 128/181/213 Cambrian RGB 251/128/95

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Ordovician RGB 249/129/166 Silurian RGB 177/114/182 Devonian RGB 153/153/201 Carboniferous RGB 153/189/218 Permian RGB 103/198/221 Mesozoic RGB 127/173/81 Triassic RGB 103/195/183 Jurassic RGB 77/180/126 Cretaceous RGB 127/195/28 Cenozoic RGB 225/225/0 Paleogene RGB 255/179/0 Neogene RGB 253/204/138 Quaternary RGB 255/255/77

Symbol Standardization. The following page presents some of the most commonly used geologic symbols. A complete list may be derived from the Federal Geographic Data Committee which standardizes all geologic symbols.

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Preparation. Before mapping, the geologist conducts a walkthrough of the selected area. The geologist looks for and finds any general trend in the strike. The purpose of looking for a trend in the strike is to assist the geologist in establishing traverse lines. Traverse lines are straight lines that traverse the working area in a parallel manner. The traverse lines should be perpendicular to the general trending strike if there is one. This will reveal as much geology as possible during the mapping. Simply following the trend of the strike would be boring. For small areas, geologists may

simply walk the area but for large detailed projects it may be necessary to emplace stakes at the beginning and end of each traverse line and run a line between the stakes. The distance between the lines depends on how much accuracy is needed as well as the visibility between the lines. In wooded areas, traverse lines may be as close as 5 meters apart. The geologist is not locked into walking on the line; this is a guide to ensure the area is properly studied.

The geologist should be equipped with at least the following items: Transit compass GPS Grid line paper Number 2 pencils Marker Protractor Clip board

Pocket knife Hand lens Rock hammer Eye protection Sample bags Backpack

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Adequate food, water, sun screen, insect repellent, flash light, extra batteries for everything, and rain gear should also be available. In the example map on the following page, the geologist found that there is a trend in the strike of N54E during the walkthrough. Because of this traverse lines were ran N36W to

ensure they were perpendicular to the trend of the strike. If a trend was not found it is reasonable to conduct traverse lines in a grid.

The field map should have the minimum information: Map name – should be related to the area of study Person developing map Purpose of the study Date

Legend Scale North arrow

While mapping, the geologist carefully draws each geologic feature and annotates it with a number. This number corresponds to the notes and samples taken.

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The Field Map.

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The Mapping Story The geologist begins in the northwest corner of the mapping area and proceeds southeast along the A to A’ route as shown on the map- This A to A’ line is not really a route but a line drawn on the map by the geologist that is orthogonal to the general strike of the geology and will be used in the lab to visualize the subsurface geology. The geologist first finds a schist outcrop. Pulling a slightly rusted rock hammer from its sheath, the geologist looks for and finds a section of rock that may be easily removed. Hitting the outcrop several times sent a sharp piece of rock up and into the air; a subtle reminder to put on the safety glasses. Removing the sample and examining it through a hand lens revealed tiny garnets that had been sheared in a counterclockwise direction. This was interesting. The geologist labeled the sample “FMN 1a” to mean “Field Map Name”, outcrop 1, “a” being first sample from outcrop 1. Because it was a foliated rock with some folding the geologists carefully put the rock sample back on the outcrop and marked its orientation so the foliation and folding could be understood when the rock was returned to the lab. After the specimen was properly marked and documented in the note it was safely bagged. The uneven surface of the foliated rock was difficult to take a strike a dip on. At last, a small section was found smooth enough for the task. Thinking, “Am I a pretzel or a geologist?” The geologist had to contort to new forms to read the dip angle on the Vernier. The notes were begun with “1. Schist outcrop - Green colored metamorphic rock with a greasy luster bearing garnets 2 mm in diameter exhibiting counterclockwise shearing. The garnets are spaced sporadically. The sample shows a gentle2 cm folding with a regular rhythm orthogonal to the foliation. Strike and dip is N54E 25.” The location from where the sample was removed was observed with the GPS and also recorded in the notes. After finishing the note, the geologist thumbed through several screens on the GPS to the Way Marks. A way mark was entered on the GPS itself; this would later be downloaded to a computer. While scrolling through the screen keyboard the battery low screen came on. Business as usual; a couple of minutes were spent 26

changing the batteries. The outcrop was paced off several times and while setting on the outcrop, the geologist drew a scale drawing of the outcrop on the geologic map and labeled it with “1”. Then using a protractor the geologist made a line on the map to represent the N54E strike, a triangle for the foliation was added to the symbol and the dip of 25 was written. Thinking for a couple of minutes which way to put the swirl to show counterclockwise motion in the shear the first outcrop was complete. Walking just one more meter the geologist encountered another outcrop. This was a basalt outcrop, about 1 meter high and somewhat flat on the top. Once again a sample is sought. Finding a suitable piece and striking it with the hammer sent the tool recoiling and vibrations up the arm. Yeap, this was a much harder rock. More effort was involved in freeing the sample. The sample was examined under the hand lens, bagged, and labeled. The geologist climbed on top of the rock. The heavy lugged boats clung to the rock as it was ascended. From atop the outcrop it was observed that the basalt had a general trend but stopped in the southwest direction, off set, and began again. Thinking, “How odd,” taking a compass bearing in each direction, a GPS reading, and pacing the outcrop off, the geologist was able to accurately draw the outcrop on the map. A note was also entered. “2. Basalt outcrop protrudes from ground about 1 meter. Black dark grey aphaneritic igneous rock. Has a uniform body that trends N54E. The outcrop stops, off sets, and begins again in the southwest.” The coordinates of the sample were documented on the sample bagged, and annotated in the notes. Climbing down off the rock was much easier then climbing up and within a meter the geologist encountered another outcrop. Examining the outcrop closely showed that it was the same schist as seen before. It had same gentle folding and the garnets were the same size. While pacing off the outcrop to annotate it on the map the geologist found that the outcrop is in contact with a banded iron outcrop. This is exciting, the geologists starts to draw conclusions about the previous environment 27

where the rocks formed, imagining a sea floor near the end of the Precambrian but the geologist stopped. Think, “I haven’t learned enough about the area to start drawing conclusions." The banded iron outcrop looked rather ugly with the red oxidation coating. A lot of effort was involved in collecting a sample. The rock that ultimately separated from the outcrop was much larger than wanted but after examining it under a hand lens it was found to be a gem worth weighting down the backpack. Silver to black colored banded iron with metallic luster and narrow bands of chert with waxy luster. Small vugs containing various metallic crystals demanding further examination under a microscope with some calcite and a larger vug was also present containing dark grey botryoidal iron. The sample was labeled as “FMN 3a” and a detailed note was lovingly entered for this metallic specimen. As banded iron is a sedimentary rock a dip angle was sought. While taking the strike a lot of care was taken to ensure the metallic content of the rock did not disturb the compass bearing. Moving the compass closer and closer to the rock did not change the bearing. This probably indicated that there was little to no magnetite in the banded iron. The strike and dip were found to be N54E 25. This and the UTM coordinates were also entered into the notes. While sitting on the outcrop and drawing it to scale on the map sheet the mosquitoes insisted that the geologist should feed them. Applying some repellent seemed to serve as a restraining order as they buzzed around the face and ears but didn’t land. This was a low point in the topology and there was some standing water between here and the next outcrop. Moving through the smelly stagnate water the geologist came to the next outcrop some two meters away. This was the same banded iron except it was dipping in the opposite direction. This meant that the area of standing water was obviously the low point in a syncline and the top of the basalt outcrop was probably an anticline. Although there was an urgency to move away from t he mosquito breeding ground the geologist mapped the outcrop with as much care as the previous outcrops—and then moved out quickly. The geologist continued to move along the A to A’ route carefully mapping another basalt outcrop of equal in height to the previous basalt outcrop, another schist outcrop, and another banded 28

iron formation. There were three additional outcrops to the east side of this traverse and all three were inferred with dotted lines to connect to those mapped on the traverse. The two segments of basalt that were disconnected and offset needed a closer examination. The geologist found that each of these two segments of basalt were about the same thickness as those mapped on the traverse and seemed to be the same rock. Each was found to be about a half meter shorter in elevation than the basalt outcrops to the east and their offset was about 1.5 meters trending S36W. Both were accurately mapped. The geologist was confident that this was a left lateral slip fault. Drawing it on the map and labeled it as “4” there was a personal tug of war as to whether the fault could be continued to the southeast on the map even though there was no visual evidence to support that it had continued to fault. Ultimately the geologist continued the fault on the map but annotated it as inferred and labeled it as “5.” The fault was described in the notes and the reasoning why it was believed to be a fault were carefully detailed and why the other segment was presented as inferred was detailed. As the tops of the basalt were relatively flat they were given geologic symbols showing them as flat. The geologist also believed that the two basalt outcrops were dikes but represented the hinge of two anticlines— the dikes were possibly the cause of the syncline between them. The geologist stopped for lunch and reviewed the field notes and the map. After enjoying a sandwich the geologist crisscrossed the area to ensure nothing was missed. All outcrops were mapped. A good rock sample was obtained, labeled, and entered into the notes at each outcrop. The geologist was already mentally preparing the geologic report.

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Chapter 4 - The Geologic Report Without a report, all of the effort the geologist puts forth in the field is lost. It is much more than simply writing a report, the observations made and the data collected must convey

information in a meaningful manner. Scientific Technical Communication are keywords in writing for all fields of science. This field of writing requires the document to communicate.

Purpose of Geologic Reports. The purpose of the report was predefined when the geologic project was planned. The purpose may have been academic or required in support of an engineering or mining project. Geologic reports have many purposes and no one purpose is better than the other

however the purpose may dictate an emphasis. There may be special emphasis on metallic minerals or on salt. Other projects may focus on faults to help discern the structural integrity of a possible waste disposal site.

Report Format. Presentation does matter. The presentation of the report matters as much as the accuracy of the content. The data, tables, graphs, diagrams, photographs, and maps should be presented throughout the report.

focus on subject material in field that is relevant to the purpose. The format is not to be taken for granted. The geologic report may be just a small part of a much larger presentation. The source requiring the report may have a predetermined format, specific font choice, preference in the paper’s weight, and even what media will be used to convey the report.

The format should be established during the project planning. Having the format established during the planning phase allows the geologist to 30

The following is offered as a guideline if no format is defined:

Title of Project Name of Geologist(s) Date

Abstract 1) Introduction a) The Project’s Purpose b) Geographic Location c) Methodology Used

2) Local Geology 3) Regional Geology a) Rock Unites b) Fossils c) Lithology

4) Structure a) Faults b) Folds c) Unconformities

5) Summary 6) References

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Target Audience. Target Audience is a term that applies to Scientific Technical Communication and means who the document or report is prepared for. In some aspects target audience analysis is nearly a field of science of its own. Here teams identify the target audience’s vulnerabilities, susceptibilities, and even what forms of media the target audience best relates. The target audience may be a team of geologists, other scientists, venture capitalists, executives, or even politicians. The document or report prepared should be for the specific target audience—the people who will be reading the report and making decisions. There are large cumbersome dictionaries dedicated to the field of geology. There is probably no other field of science that fabricates so many complex and

entirely unnecessary words. If the target audience is not a group of geologists the use of geologic terms prevents the document from communicating the content to the reader. Many reports ultimately end up in presentations for executives or politicians who have to make a decision on whether a project will be funded or not. Ensure the report communicates to the reader. If necessary develop more than one report, one that serves as a presentation that anyone can understand and another made available for those who understand the jargon of a particular field of science and want detailed information that may bore someone else. It has been said here once but cannot be overstated, presentation matters.

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Bibliography. FGDC Digital Cartographic Standard for Geologic Map Symbolization, 2008 USGS Color Code, 2005 Manual of Field Geology, Compton, 1962

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