PRINCIPLES OF FIELD GEOLOGY Field Work Organization

What does the field study? Field studies solve geologic problems where the earth materials and structures can be identified easily by considering their field relations with other related geological features.

KINDS OF FIELD INFORMATION 1. Listing direct straightforward facts of geological observations and measurements Rock types, name and textures in hand specimen, The strike and dip of beds and geologic relations between the rock units. Field worker should be artist in gathering and organizing objective field data. 2. Discussion of field data implies specific genetic conditions or environments. To consider what happened in past and clarify the host of interrelated data. 3. Interpretation of the discussed field data will provides a sequence of age relations and put geologic events in classical orders. Experience of field geologist and how much geological theories he involved. Descriptions and drawings of structures and field relations by constructing cross-sections and block diagrams to supports own interpretations of field workers.

PLANNING FOR THE FIELD WORKS 1. The problem Should be clear for solving carefully concocted specific questions . It should be clear not only what is to be accomplished, but also who will be results-interested. A reconnaissance to (1) make sure the area is suitable for the topic selected and (2) plan the field work in light of time and funds available. 2. Questions about the field topics Determining the problem of field project and also reconnaissance of the area should be followed by covering some questions that are necessary for any field notes: Rock units----- description, continuity, akin elsewhere, fresh, exposed enough, fossil contents … Structures----- regional, local, types, ………

PLANNING FOR THE FIELD WORKS, Cont. 3. Preparations for the field Field reconnaissance, read the published and unpublished literatures, to: See what they may contribute to the topic or question of the study. prepare or obtain suitable field equipment such as: Field equipments are many and the needed ones are related to the type of field works. The most common equipments are aerial photographs, landast images and geologic and topographic maps, altimeter, hand lens, diluted hydrochloric acid, geologic hammer, compass, GPS, first aid kit, eraser, pen, pencil, ruler, colored pencils, papers, paper-holder, notebooks, sample bags, sterographic net, camera and camera's films and batteries. For mapping purposes, topographic maps and aerial photographs: Advantages of Aerial photographs are: May show some geologic features that do not appear on topographic maps. Location can be made on them accurately and quickly because they show many details such as individual trees and outlet or inlet distributary streams. Disadvantages: Areas covered by forest are very difficult to map on it. Aerial photographs can not be used easily to obtain three-dimensional views of the terrain. Nevertheless, the data collected should be transformed frequently to a topographic base. - Topographic maps might be preferred due to some reasons: Less expensive and are more useful in mapping quadrangle-size areas, Give three-dimensional view through drawing geological cross-sections, Can be enlarged to give more spaces for plotting geologic features and locality numbers.

PLANNING FOR THE FIELD WORKS, Cont. 4. In the field The geological mapping before sampling….. The localities are numbered in order to relate them to field notes that describe the features and well represented rock samples. Structure elements are measured such as strike and dip of bedding and any other surfaces such as faults, joints, foliations, lineations, axial plane and fold axis are plotted at once on the map with appropriate geological symbols. Localities of collected fossils, rocks or minerals are plotted as are sites where photographs are taken or where drawings are entered in the notes to record structural relations too small or too complex to map to scale. Thus the map becomes a picture of the formations and structures that can be drawn to scale and orientation in space as well as geographic record of all other data and ideas recorded.

PLANNING FOR THE FIELD WORKS, Cont. 5. In the field camp or office Routine works should be done during evening or on an occasional office day. Data are transferred frequently from separate field sheets or aerial photographs to an overall base map that is colored lightly to emphasize the distribution of rock units and structures. The transferring is done frequently to see the geology develop concurrently with field mapping, and thereby keep the project moving ahead as planned. Other important routines are to read field notes and study the map and rock samples together in order to examine recent discoveries and think over geologic puzzles. These reviews plan the field strategies of the next few days or weeks. An important routine is to write summary descriptions of rock units and large structures as field work progresses including interpretations with well presented cross-sections and drawings which are invaluable basis for writing the final report.

PLANNING FOR THE FIELD WORKS, Cont. 6. Completing field works Questionable structures and intrusive contacts should be reexamined, in the central theme of study. Intensive parts of the study are expanded during second field season. The geologist can anticipate the final report by doing the following: Comparing the office map to field sheets and notes. Selecting cross-section lines and preparing complete pencil drafts. Reviewing notes and summery descriptions to be sure that all units and structures are described fully; rock and fossil samples will be adequate to resolve interpretation; and structural data are sufficient to define structures and episodes of deformation. Writing an outline of the geologic history. Writing report should be supported by maps, cross sections, drawings in three dimensions specially the oriented blocks and photos. Exercises: List in simple orders the steps that make your field trip successful. How does geologist anticipate the final report in the last day of field work? Topographic maps are much better in field mapping in Egypt rather than using aerial photographs (Do you agree? explain).