如题所述
One should clearly and accurately record all observed geological phenomena in a field notebook.Records of the field information are important for interpreting data obtained later in the laboratory and for interpreting the geologic history of the area.The quality of the records has a direct bearing on one's understanding of the field data.One should rigorously use a consistent,common terminology and a clear,accurate writting style.Geologic maps are also crucial records of field data and relationships.
1.Text record S
A good text record is fundamental to field research.Such a record should include the purpose of the work,a description of the main areas to be investigated,date,location,weather conditions,observers,geological data and identification of samples and photographs.A short summary of each occurrence of each day's work is also useful.
Long-term field work requires consistent methods and records(Fig.2-3).Generally a 2H pencil is best for recording data.One should record for each day,the date,weather conditions,location,route number,start and end point of the route,specific stops,descriptions,measured data,and sample and photograph numbers.The record should follow a consistent format,e.g.,line,point,sample,photo,etc.
All data must be recorded in the field rathert han in the evening when iti sd ifficultt o remember specific details.Corrections to the text should be marked but information should not be erased.Also the page numbers in the field book should be continuous and no pages could be torn out of the book.
It is important that the field book be used ONLY to record geological phenomena,and notf or any other purpose.Be sure to look after the book and not lose it.A loss should be reported immediately to the person in charge of the class.
2.Field map record
Field drawings,sketches,profiles and geological maps are clear and concise statements of geological phenomena,in particular,the relationship between different rock units.Some geological observations may be difficult to express clearly in words,but can be show on a map or drawing.Because geological maps always include some interpretation,they provide a different perspective than a simple photograph.A geological map is a simple,clear way to show geological relationships and should be easy for the reader to interpret.
Fig.2-3 Written record format for field record book
Field sketches are generally drawn on the page opposite the written record.The mostc ommon sketches are drawings of outcrop features,stratigraphic columns and geological cross-sections.
1)A sketch geological cross-section(Fig.2-4)records geological data along or between outcrops.It shows the relationship of various units and gives a view of any structural features.Cross-sections usually involve interpretation of geological relationships and thus provide a different perspective than a photograph.The steps to follow in drawing a cross-section are:A)select the outcrop or feature to be investigated; B)determine the best orientation of the cross-section; C)determine the scale required; D)show relationships to be described;E)label the section with a name,legend and direction.
Fig.2-4 Format for a sketch geological cross-section
2)Geological maps provide a record of the surface expression of various geological units and structures.Like a cross-section,a map involves interpretation and extrapolation of data in areas where outcrops are poor.The steps to follow in drawing a map include:A)select the map area(whatever is necessary to display the geological content）; B)select an appropriate scale; C)sketch the geological contacts and structures;D)1abel the map with a north arrow,a scale,a name and alegend.
3)A temporary geological cross-section is a quick sketch of the geo1ogical features along a route to provide a general guide to the area and to help plan the investigation.It is based on approxim ate relationships rather than detailed,measured data.However,the cross-section must be correct,based on observations,but not im agination.The steps to follow for drawing a tem porary section include:A)determ ine the direction of the profile(baseline）,which is generally perpendicular to the strike of stratigraphic and structural features; B)select an appropriate scale so that the profile has a reasonable length,but also shows all of the geological phenom ena; C)draw the topography along the line of the cross-section;D)draw the geological features using a protractor to project strikes and dips; E)use common patterns and names for the geological features; F)label the section with an appropriate name,legend,scale,direction and location.
Note that all drawings,whether they are sketches,maps or cross-sections,must have a name,scale,direction,legend and geological contents(Fig.2-4).The drawings should be clear,clean and easy to read.
