Using Sieving and Unknown Sand Samples for a Sedimentation-Stratigraphy Class Project With Linkage to Introductory Courses

Abstract

ABSTRACTUsing sieving and sample “unknowns” for instructional grain-size analysis and interpretation of sands in undergraduate sedimentology courses has advantages over other techniques. Students (1) learn to calculate and use statistics; (2) visually observe differences in the grain-size fractions, thereby developing a sense of specific size ranges, weight percentages being plotted, and how grain composition and properties are a function of size; (3) are enthusiastic and observant as they search for clues of the origin of their sample, but discover that determining depositional environments using grain-size analysis is not the hoped for “fingerprinting” technique; and (4) enjoy learning the geographic origin and depositional environment of their sample. Plus, sieving equipment generally is less costly to acquire and maintain than “black box” techniques, and sieving is a commonly used procedure in industry. Using unknown sand samples results in some students making “incorrect” interpretations, which allows for illustrating that a scientist may have an excellent data set and a valid interpretation based on that data but, although the data are sound, the interpretation may be erroneous. Moreover, using a suite of unknowns allows students in a class to collectively be exposed to sands from a range of environments and geographic locales without the need for local sediment-rich environments. Building a set of unknowns is aided by recruiting students in introductory geology courses to collect and document samples during their school-break travels for future “unknowns,” thereby linking courses and creating interest among nonmajors. When these students venture into the field to collect a sample and characterize the environment, they are enticed into thinking about sedimentary processes and possible anthropogenic effects, such as beach nourishment, while on break.