STANDARDIZED FIELD METHODS FOR THE CHARACTERIZATION OF FRACTURES IN SUBAERIALLY EXPOSED NATURAL ROCK STUDIED IN THE CONTEXT OF SURFACE PROCESSES

Many geoscience subdisciplines, like sedimentology and soil science employ widely-accepted standardized methods to acquire suites of data that reflect discipline consensus for the “basic” minimum data of any study. Despite an increasing recognition of the wide-reaching role that fractures play in Earth and planetary surface processes, hazards, weathering, building stone preservation and landscape evolution, a universal standardized method is lacking for fracture characterization in natural settings outside of rock cores. Particularly in published geomorphology studies, the methods vary wildly, and many lack sufficiently detailed decision-making criteria to be reproducible. Before we can begin to fully understand, compare, and contrast rock fracture data across research and research sites, we must agree on a defining set of rock fracture data and data collection methods. To that end, in this work we propose a fracture measurement field manual that employs the tried-and-true state-factor approach of soil science (Jenny, 1941) as a basis to: 1) define a standard suite of baseline field fracture and rock data metrics to be used to characterize fracturing in naturally exposed rocks and 2) detail best practices for field site location, study design and collection of these data both from our experience and from existing studies from geotechnical fields. The standardized set of rock and fracture data proposed herein is focused on measurable, nondestructive observations – without interpretation - that we believe apply universally across field areas. These methods are designed to be applicable and translatable to both natural outcrops and to individual clasts – like boulders in a talus field. We solicit and welcome feedback from PRF2022 attendees to refine the content of the manual prior to its submission for publication.