A PHENOMENON ALIGNED TO NEXT GENERATION SCIENCE STANDARDS PERFORMANCE EXPECTATION MS-ESS1-4 AT THE DESERT OF MAINE IN FREEPORT

Several Earth Science Performance Expectations (PEs) of the Next Generation Science Standards are written in problematic ways. Most states now base their K-12 high stakes assessments on these or similar standards and test developers often have orders to treat PEs as literally as possible, so it is beneficial to examine problem PEs. One such PE is Middle School ESS1-4, which focuses on the geologic time scale. MS-ESS1-4 is written in a way that makes finding phenomena that align to it difficult, because whereas the PE’s text recognizes the time scale as a device to organize Earth’s 4.6-billion-year history, the science knowledge component states that analyses of rocks yield relative, as opposed to numerical, ages. Workable phenomena are thus those that allow students to determine a relative age for a horizon or fossil by comparing it to a different, numerically dated horizon. Such a phenomenon has been discovered at the Desert of Maine in Freeport. The Desert is an anthropogenic disturbance set in several hundred acres of sand. The deposit accumulated through actions of post-glacial-retreat winds, probably from ~12,700 – 12,000 years ago, after which plants stabilized it. 19th Century farming partially re-exposed the sand and allowed historic winds to work it, resulting in the dune field which persists to this day. Excavation of a dune in September 2020 to search for a buried spring house revealed a contact between the historic dune sands and underlying glaciomarine deposits. Due to characteristics of the local geology, the contact is a phenomenon that falls nicely within the contrived situation demanded by the wording of MS-ESS1-4. The glaciomarine deposits relate to the retreat of the Laurentide Ice Sheet, and coincident marine transgression, through the area ~16,000 years ago. This is a major event in Earth history, as stipulated by the clarification statement of MS-ESS1-4. There is radiometric age control on the glaciomarine deposits from nearby Mytilus edulis shells, and historic age control on the spring house’s construction (1938) and burial (1963). Thus, students can address this phenomenon by determining a relative age for the dunes with respect to the spring house and glaciofluvial deposits. This phenomenon adheres to the situation set up by the wording of MS-ESS1-4 and works on assessments or in the classroom.