From Ice House to Iceland… A Summer Adventure like No Other

Hello! We’re Danielle and Tessa, and this summer
we’re working in Dr. Sarah Principato’s lab
focusing on Earth System Science.

Hammer? I hardly know’er!

Hi! I’m Tessa and I’m a rising senior majoring in Environmental Studies. Working with Dr. Principato has been a great experience for me as I plan to go to graduate school for geoscience. For X-SIG this year I am doing lab work for my honor’s thesis, which is a methodology assessment of relative age dating tool called the Schmidt Hammer (SH; pictured below). Specifically, I am focusing on the efficacy of this tool in providing relative ages for glacial and periglacial landforms in the Mid-Atlantic US and Iceland.

The SH works by deploying a plunger with a specific impact energy onto a rock’s surface. A reading of the surface hardness is then displayed on the scale, ranging from 10-100. This hardness can be used to estimate relative age under the assumption that surfaces which have been uncovered by ice for a longer period will have been exposed to more weathering, and subsequently have a lower surface hardness compared to rocks which have been exposed for a shorter time.

To evaluate the effectiveness of this tool, I measured the hardness of boulders in boulder fields across Pennsylvania and Maryland, boulders on moraines (ridges of sediments deposited by glaciers) in Iceland, and bedrock outcrops in Iceland. I evaluated five boulder fields across the Mid-Atlantic, using the SH on ten boulders with ten impacts per boulder. In Iceland, seven landforms (a mix of bedrock outcrops, moraines, and lone boulders known as glacial erratics) were evaluated, also with ten impacts per surface.

In PA and MD, I am hypothesizing that boulders which are closer to the paleo-ice margin (the furthest extent that the glacier reached before retreating) will yield lower average SH hardness values than boulders further from the paleo-ice margin. In Iceland, I am hypothesizing that boulders which are known to be older based on other dating methods such as radiocarbon or cosmogenic nuclide dating will have lower average SH hardness values than their younger counterparts. We had the fortunate opportunity of working with a researcher from the University of New Hampshire, Joe Licciardi (pictured below), who will be performing cosmogenic nuclide dating using chlorine-36 on some of the landforms we measured. This will provide numerical ages to which I can compare my SH hardness values.

         The main purpose behind this assessment of the SH as a relative age dating tool is to provide a lower-cost, more accessible alternative or complement to the expensive numerical dating tools we currently use. Analyzing rock samples with radiocarbon or cosmogenic nuclide dating techniques is time consuming and requires high-tech facilities which liberal arts colleges such as Gettysburg do not typically house. With my work this summer, I am hoping to provide an economical alternative for future undergraduate projects in relative age dating of glacial landforms.

         The most exciting part of my research this summer has by far been our fieldwork in Iceland. Here are some of the highlights!

We got to climb on the lava flow from the 2021 eruption
of Fagradalsfjall.
We walked (dangerously close to) a crater’s edge.
We admired the national flower, dryas octapetala.
And we enjoyed the breathtaking views Iceland has to offer!

From Ice to Water…

Hey there – I’m Danielle, a rising senior double-majoring in Chemistry and Environmental Studies. With an interest in geoscience, working in Dr. Sarah Principato’s lab is a perfect fit for me! This summer, I’m performing a local water quality study that will extend into my senior capstone project. 

We all can agree that water is important. Freshwater specifically has countless uses for our human population. Just to name a few, we depend on freshwater for drinking, sanitation, agriculture, industry, and recreation. Freshwater ecosystems are also quite biodiverse, supporting over 100,000 species.

Accounting for only 2.5% of total global water, freshwater is a limited resource. Since freshwater is important and limited, its conservation must be prioritized. Pollution is one of the most prevalent stressors on freshwater ecosystems. Here in Gettysburg, Rock Creek is a major stream. This stream flows along agricultural fields, which use fertilizers and pesticides to increase yields of healthy crops. It goes on to flow under Route 30, a major road where during storms, urban runoff may contaminate Rock Creek with metal pollution. Further south, Rock Creek flows past the Gettysburg Municipal Authority wastewater treatment plant, which discharges millions of gallons of treated wastewater into the stream each day. Some areas along Rock Creek have a riparian buffer, which contains natural vegetation such as trees to improve water quality through control of non-point source pollution and protection of the stream environment. With this background information, I was prepared to ask a couple of research questions investigating water quality in Rock Creek:

  1. How do agriculture, urban runoff, and wastewater effluent affect the water quality in Rock Creek?
  2. How effective are riparian buffers in limiting contamination of Rock Creek?

To answer these questions, I am sampling at 5 sites along Rock Creek, and 1 site in a tributary to Rock Creek (Figure 1). Site 1 is the headwaters of the stream, where there is no riparian buffer. Site 2 is a buffered area near the Gettysburg High School. Site 3a is right under Route 30. Site 3b is in a tributary to Rock Creek called Stevens Run, which runs right through the Gettysburg College campus. Site 4a is just upstream of the wastewater effluent discharge point, whereas Site 4b is just downstream of the discharge point (Figure 2). For ten days at the start of XSIG, I sampled from each site daily. I plan to sample once a week until the end of October to see potential seasonal variation at each site.

Figure 1. Sample Collection Sites Figure 2. Wastewater Treatment Plant Sites

What exactly does water sampling entail? In order to assess water quality, countless variables can be used. In the field, I use portable meters to measure temperature, pH, total dissolved solids, electrical conductivity, dissolved oxygen, and oxidation-reduction potential. I also take a sample back to the lab from each site, where I measure concentrations of phosphate, nitrate, and ammonia in the water. I hypothesize that Site 1, an area with less riparian buffer, will have higher concentrations of these chemicals. Using the Inductively-Coupled Plasma Atomic Emission Spectrometer in the Physics Department, I’ll be looking at trace concentrations of metals including zinc, lead, and iron. I predict that Site 3a and 3b, which are located in more urban areas, will have higher levels of zinc, lead, and iron due to stormwater runoff. I also plan to test for the presence of fecal coliform bacteria, which indicates contamination from human waste. Even though the wastewater treatment plant treats water according to federal environmental standards, I am interested in seeing if this bacteria is present at Site 4a and/or 4b.

In this photo, I’m using a portable meter to
measure pH and temperature.
Tessa showing off a water sample under Route 30.

Through analysis of these variables, I hope that my pilot study will open the doors for more specific studies on Rock Creek as well as shed light on the different pollution pressures present in Rock Creek. I will share my findings with the Watershed Alliance of Adams County (WAAC) and look forward to comparing my data to their past data and hearing their feedback for future studies.

Thanks for reading our blog post!

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