Hiking 9.5 million year old metamorphic rocks, snorkeling at the edge of the caldera shelf, and cliff jumping from Spartan ruins wakes you up, but it pales in comparison to the intense brain blasts NAU in Greece has generated. It has tied everything I previously learned into three big, life-altering weeks. Through each geology course I have taken, I studied the processes driving volcanic creations and eruptions and how they are ultimately dictated by their magmatic properties; NAU in Greece took all my university knowledge and threw it at the Santorini Volcanic Complex to create my deepest understanding of volcanic properties thus far.
I can’t tell where my journey will end, but I know it started with Geologic Disasters two years ago when I first had Lisa Skinner as a professor. Through her captivating lectures, I first learned about magma properties and silica content which are the ‘building blocks’ for volcanoes. If you think of silica as debris in magma, then the more silica there is the slower the magma moves and the higher its viscosity is. If a magma chamber is more viscous, then it is harder to erupt and results in more forceful explosions of felsic magma. Thus I learned the relationship between mafic or felsic magmas, their silica content, and their explosions. But what determines how much silica a magma chamber contains?
I distinctly remember the day I was sitting in Dr. Michael Ort’s Physical Geology class when I learned about magmatic differentiation and Bowen’s Reaction Series— I sat there, mind blown, as I had my first geology to chemistry connection. Magma at great depths is mafic, with low silica content, and goes through magmatic differentiation, or evolutionary processes, as it rises. This changes its silica percentage and can morph the fluid rock into the felsic range. This can be done by mixing two magma chambers that have different compositions, melting and incorporating the country rock around the magma plume, or having parts of the magma plume crystallize into minerals over time.
Norman L. Bowen first recognized a pattern in the order of minerals the crystallize from magma as it ponds under continental or oceanic crust. Typically, the first minerals to crystallize out of the magma are low in silica. Consequently, if you remove elements and minerals that don’t have much silica, the ratio between the remaining elements and the silica increases; just like if you eat all the M&M’s in trail mix, the percent nut composition is driven up. The amount of silica crystallizing determines how mafic or felsic the minerals created are.
Bowen’s Reaction Series starts with mafic olivine and pyroxene (my two favorite minerals— they’re green!), and moves toward intermediate hornblende, and felsic quartz which is high in silica content and therefore one of the last to crystallize. So as the magma evolves, the minerals either form or re-crystallize along Bowen’s Reaction Series as it goes through varying magmatic differentiation. Is it bright in here or are there just too many lightbulbs going off?
The translation from learning about volcanoes in the classroom to studying them in the field started with Historical Geology and Introduction to Field Methods and Report Writing. Dr. Lee Amoroso taught me how to interpret a stratigraphic column, which is a graphical representation of the layers of rock beds and their relative sorting, rock composition, and thickness; for an in depth look, see Allaire Conte’s post An English Major’s Guide to Stratigraphic Columns.
Extending the stratigraphic columns a step further, Taylor Joyal taught field methods to describe and record geologic features in the field. I learned to use a Brunton Compass, which is a geologic compass for determining the directions and angles of rock units making it the coolest geology tool ever! I was learning to record the bearing and slope of rock outcrops, as well as how to roughly sketch what I see into my field notebook despite not being even remotely artistic.
NAU in Greece has incorporated each of these classes into its dense curriculum. Almost everything I learned about volcanoes changed from simple theoretical situations of one volcano taught in Geologic Disasters to volcano complexes in our Greece pre-departure lecture. As magma differentiates, the volcanoes produced change according to what the chamber’s composition becomes. When the chamber starts as mafic it produces basaltic or basaltic-andesitic shield volcanoes and cinder cones. Changing the silica composition creates intermediate to felsic magma resulting in rhyolitic or rhyodacitic volcanic domes and composite cones.
A volcano’s type depends on the magma’s evolutionary stage; each chamber can produce varying types of volcanoes above it to develop diverse volcano complexes. Uniquely enough, the oldest volcanic rocks exposed on Santorini is a rhyodacitic dome on Cape Akroteri which is felsic instead of mafic. Mafic volcanic rocks that predate this dome could exist, but they are not exposed above sea level. As a class, we went out and began to measure, observe, and draw the outcrops of each volcanic rock setting of Santorini’s Complex including: shield volcanoes (mafic) of Megalovouno and Skaros, ignimbrite (pyroclastic deposits) from the Minoan Eruption, basaltic to andesitic shields and domes (mafic) of the Kameni Islands, and a cinder cone (mafic) at Red Beach.
I’ve been told students don’t become geologists until they take their junior level classes such as Mineralogy or Sedimentology and Stratigraphy, when they’re wiser and they’re older, but I believe I have taken the largest singular and most impacting step in my geologic education with the chance to travel the world through NAU in Greece. Not only is the material more advanced and thus more stimulating to learn, but the caldera is our classroom and the rocks are our teachers. Professor Skinner has built a unique, in depth course that combines material from Physical Geology, Historical Geology, Geologic Disasters, and Field Methods and Report Writing. Basically, Geology 101, 102, 103, 104, 112, and 240 are all compressed together into a fast paced and all-encompassing coarse load.
Sitting on Cape Akrotiri and studying the minerals in a block taller than I can reach, which is nearly 2.7 meters (8 ft.), made me yearn to learn all I can in Mineralogy. Measuring the thickness of the Minoan Eruption Phases and creating my own rudimentary stratigraphic column drives my motivation to discover what I can do in Sedimentology and Stratigraphy. I want to be a leader in my field, and NAU in Greece has lithified my desire to be just that. I cannot wait for fall courses to begin— even though nothing will compare finding myself in Greece’s most stunning caldera.