To find out about Carleton’s past, the obvious first stop is the Carleton Archives, where digitized copies of the Carletonian, official records, past lectures and interviews, and photos of campus (often missing its current, familiar structures) are at one’s fingertips. Digging through these pieces of evidence can help us figure out what Carleton as a community was like years ago, but where do we turn to find out more about Carleton’s natural history? Though much can be learned from Arboretum records and clues within the visible landscape, many of the answers rest right beneath our feet. Last week, the Student Naturalists had a chance to be led around by two students from the Geology of Soils class, who showed us their current projects on interpreting soil in many areas of the Arb. Making holes in the ground several feet deep and wide enough to climb into, these soil investigators examine the different layers of soil – called “soil horizons” – and think about where that soil came from, its composition, and what that means in relation to the Arb’s natural history. Sometimes, soil horizons are fairly easy to identify – a top layer of sandy, silty soil found in a pit dug near the river was certainly deposited by last year’s giant flood. Other horizons are more of a mystery. For example, the pit dug in the fields of the Carleton Farm showed a curious band of sandy, unevenly distributed soil among otherwise more fertile, dark earth. Though students in the Geology of Soils class have theories as to this mystery soil’s origin, such as it being the remains of a dirt road for an area made for livestock, its true story has yet to be fully unearthed. Yet, despite the challenges in soil identification, the investigation of the earth beneath our feet leads to many interesting clues into the dynamic life of the Arboretum, proving that sometimes the only way to get an answer is to keep digging for it.
-Rae Wood, for the Cole Student Naturalists