Strike and Dip By Donald J. Wagner Franklin High School 1.Stick a 1-foot piece of masking tape to a flat table top. Align the tape as directed by the teacher. 2.Line up the edge of the short wooden board with the masking tape, and prop the board on a textbook. Align the mark on the board with the edge of the book. This board represents a tilted rock layer. 3.Obtain a piece of wire and insert it in the center hole of a plastic protractor. 4.To measure dip angle, place the wire and protractor on the tilted board, with the wire parallel to the masking tape and the 90 mark on the protractor straight down. An index card, one edge on the table, the upright edge aligned with the 90 mark and the wire, will assure this. The angle of the dip is read where the upper edge of the board intersects the protractor. Record this dip value. 5.The direction of the strike is perpendicular to the dip, in line with the masking tape. Measure the direction with a compass. Record the strike direction. 6.Repeat steps 2-5 with other boards, props, or masking tape directions as instructed by the teacher. 1.Stick a 1-foot piece of masking tape to a flat table top. Align the tape as directed by the teacher. 2.Line up the edge of the short wooden board with the masking tape, and prop the board on a textbook. Align the mark on the board with the edge of the book. This board represents a tilted rock layer. 3.Obtain a piece of wire and insert it in the center hole of a plastic protractor. 4.To measure dip angle, place the wire and protractor on the tilted board, with the wire parallel to the masking tape and the 90 mark on the protractor straight down. An index card, one edge on the table, the upright edge aligned with the 90 mark and the wire, will assure this. The angle of the dip is read where the upper edge of the board intersects the protractor. Record this dip value. 5.The direction of the strike is perpendicular to the dip, in line with the masking tape. Measure the direction with a compass. Record the strike direction. 6.Repeat steps 2-5 with other boards, props, or masking tape directions as instructed by the teacher. 30 minutes None listed Clarify the concepts of strike and dip. Measure strike and dip of a simulated rock outcrop. Clarify the concepts of strike and dip. Measure strike and dip of a simulated rock outcrop. (Class of 30 working in teams of 3) wooden boards wooden wedges (optional) 10 magnetic compasses 10 plastic protractors 10 wires 10+ masking tape 10 index cards (Class of 30 working in teams of 3) wooden boards wooden wedges (optional) 10 magnetic compasses 10 plastic protractors 10 wires 10+ masking tape 10 index cards This exercise is designed to clarify the concepts of strike and dip, and possibly practice before a field trip. Informal observational evaluation may be sufficient. If a grade is desired, simply check the student records of dip angle and strike direction against your predetermined correct answers. More advanced students should be more accurate. None listed “Grade level” depends on ability. Students should be able to read a compass and a protractor. Assemble the “rock units” beforehand if you want two or more angles to measure. Wooden wedges are available at hardware or building supply stores. To allow the teacher to check the accuracy of the measurements, have the students orient the masking tape in a specific direction (same for all, different?), use a specific book as a prop (their science text) and align the book with marks you have put on the boards (see figure). The protractor must be held so that the  line is perpendicular (see figure). “Grade level” depends on ability. Students should be able to read a compass and a protractor. Assemble the “rock units” beforehand if you want two or more angles to measure. Wooden wedges are available at hardware or building supply stores. To allow the teacher to check the accuracy of the measurements, have the students orient the masking tape in a specific direction (same for all, different?), use a specific book as a prop (their science text) and align the book with marks you have put on the boards (see figure). The protractor must be held so that the  line is perpendicular (see figure). Objectives Materials and Equipment Materials and Equipment Time Procedures Assessment Further Challenges Further Challenges Overview Teaching Suggestions Safety Note