Category Archives: Field Trips

Pictures!

Gentoo penguins, surf, and glaciers at Corinthian Bay, Heard Island.  Image credit: Bill Mitchell (CC-BY).
Gentoo penguins, surf, and glaciers at Corinthian Bay, Heard Island. Image credit: Bill Mitchell (CC-BY).

Heard Island is a pretty magical and dramatic place. I’ve been very busy with my IT duties, radio duties, and general camp upkeep. However, I’ve managed to take a few pictures in spare moments, and the highlights are posted here.

First glimpses of the Laurens Peninsula, Heard Island, after twelve days at sea.  As this image was taken, our ship was being welcomed by large numbers of birds, particularly albatrosses.  Image credit: Bill Mitchell (CC-BY).
First glimpses of the Laurens Peninsula, Heard Island, after twelve days at sea. As this image was taken, our ship was being welcomed by large numbers of birds, particularly albatrosses. Image credit: Bill Mitchell (CC-BY).
A Heard Island cormorant flies in front of the Laurens Peninsula, Heard Island.  A tall waterfall can be seen cascading down the cliff.  Image credit: Bill Mitchell (CC-BY).
A Heard Island cormorant flies in front of the Laurens Peninsula, Heard Island. A tall waterfall can be seen cascading down the cliff. Image credit: Bill Mitchell (CC-BY).
A southern giant petrel, one of the more commonly seen birds over Atlas Cove.  This individual is a juvenile, with a wingspan nearing 2 meters.  Image credit: Bill Mitchell (CC-BY).
A southern giant petrel, one of the more commonly seen birds over Atlas Cove. This individual is a juvenile, with a wingspan nearing 2 meters. Image credit: Bill Mitchell (CC-BY).
King penguins at Corinthian Bay, Heard Island, are caught in a very dusty squall.  High winds over the nullabor, a large, flat expanse of volcanic sand, bring lots of grit with them, and are strong enough to make walking difficult.  On the other side of the bay, glaciers flow down the flanks of Big Ben.  Image credit: Bill Mitchell (CC-BY).
King penguins at Corinthian Bay, Heard Island, are caught in a very dusty squall. High winds over the nullabor, a large, flat expanse of volcanic sand, bring lots of grit with them, and are strong enough to make walking difficult. On the other side of the bay, glaciers flow down the flanks of Big Ben. Image credit: Bill Mitchell (CC-BY).
Big Ben seen in twilight from Atlas Cove.  On unusually clear nights such as this one, the summit of the volcano can be seen from sea level.  Under ordinary circumstances, the low clouds would be too thick to see up more than 1000-2000 feet.  Image credit: Bill Mitchell (CC-BY).
Big Ben seen in twilight from Atlas Cove. On unusually clear nights such as this one, the summit of the volcano can be seen from sea level. Under ordinary circumstances, the low clouds would be too thick to see up more than 1000-2000 feet. Image credit: Bill Mitchell (CC-BY).
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Split Rock Anorthosite

Looking SW from Split Rock Point (a large anorthosite block).  Note the gentle dip of the rocks toward Lake Superior.  Image credit: Bill Mitchell (CC-BY).
Looking SW from Split Rock Point (a large anorthosite block). Note the gentle dip of the rocks toward Lake Superior. Image credit: Bill Mitchell (CC-BY).

This summer, I took a field trip up to Split Rock State Park in northern Minnesota, along the north shore of Lake Superior. While I wrote a little bit about the trip, there is still a bit more to be said and shown.

Part of what makes Split Rock interesting, besides a picturesque lighthouse which I didn’t take many pictures of, is the large blocks of anorthosite. Anorthosite is a rock formed primarily of the mineral anorthite, which is a calcium-rich feldspar, and the mineral zircon—used in U/Pb dating—can be found in anorthosite as well.[1] Its appearance is generally light grey or whitish, and has relatively coarse grains (mm to cm).

Anorthosite is an intrusive igneous rock formed through the crystallization and accumulation of anorthite within a magma body. It is abundant on the Moon, and lunar anorthosites are believed to have accumulated on top of a magma ocean early in lunar history. A relatively dense magma will act as a heavy liquid, and cause the less dense anorthite to float, separating the original magma from the crystallized anorthite. These types of crystallization processes, where the magma becomes separated from crystals it produces, are called fractional crystallization, and can cause the resulting magma to be enriched in some elements or components (such as SiO2). Even with massive basalt flows, fractional crystallization can cause an occasional rhyolite flow as well, but I’ll leave discussion of the rhyolites of the North Shore for another day.

Pictured above is the view from Corundum Point, a large block of anorthosite at Split Rock State Park. Below is a close-up view of some of the anorthosite, as well as a benchmark which has been placed in the anorthosite block [Thanks to Jessica Ball (@tuff_cookie) for giving me the idea of photographing the benchmark]. Despite being far from the ocean, Minnesota is home to National Ocean Survey benchmarks.

Anorthosite with survey point, Split Rock State Park, MN.  Image credit: Bill Mitchell (CC-BY).
Anorthosite with survey point, Split Rock State Park, MN. Image credit: Bill Mitchell (CC-BY).

The name Corundum Point suggests the presence of corundum—a mineral used in abrasives—and it comes from a mining operation on the site in the early 1900s. However, the point is actually anorthosite, which was much less useful for abrasives. Between the incorrect mineral identification and a fire which burned down the crushing house, the operation was eventually shuttered.

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[1] Mark D. Schmitz, Samuel A Bowring, Trevor R Ireland, “Evaluation of Duluth Complex anorthositic series (AS3) zircon as a U-Pb geochronological standard: new high-precision isotope dilution thermal ionization mass spectrometry results” Geochimica et Cosmochimica Acta (2003), 67, p. 3665–3672. DOI: 10.1016/S0016-7037(03)00200-X

Update Upon further study, it appears that the naming convention of Split Rock State Park is to call this point Corundum Point. However, Google Maps displays this point as Split Rock Point, with Corundum Point a few hundred meters to the northeast. Regardless of the arbitrary common name, the benchmarks are on the point to the southwest.

Christmas Bird Count 2015

A red-bellied woodpecker visits a backyard bird feeder.  This photo is not from Christmas Bird Count 2015, but red-bellied woodpeckers were observed on my count.  Image credit: Bill Mitchell (CC-BY).
A red-bellied woodpecker visits a backyard bird feeder. This photo is not from Christmas Bird Count 2015, but red-bellied woodpeckers were observed on my count. Image credit: Bill Mitchell (CC-BY).

Beginning in 1900, the Audubon Society began holding an annual bird population survey at Christmas (in contrast with the earlier tradition of shooting all the birds one could). Over the years, the Christmas Bird Count (CBC) has changed and grown, but still maintains its founding principles: a census of birds, taken around Christmas.

Today, counts are organized into 15-mile diameter circles, with teams of birders tallying not just how many different species they see over the course of a day, but the number of individuals of each species. In many cases, the large circle itself is subdivided, and teams of birders will count in a smaller area. Many groups meet at or before dawn for breakfast and planning. Some finish in time for lunch, others don’t stop for much of anything until it’s too dark to bird.

This weekend, I took part in the count, with a northern section of the Faribault (MN) circle. As a college student at Carleton College, I got involved in the count around Northfield, MN (within the Faribault circle), and have gone back to join the count a handful of times since graduating. One year I was in Berkeley for the CBC, which was a very different experience: no snow, and >100 species recorded.

Our group managed to see 19 species (on the higher side for that area in my experience), and around 1400 individuals. Most of those individuals, due to the relatively warm conditions here, were Canada geese (800) and mallards (450), which could be found on the open water. In years past when cold conditions have frozen over the lake and river, the waterfowl count (and total individuals count) are much lower.

Many of the other regulars were out and about: white-breasted nuthatches, red-bellied woodpeckers, goldfinches, crows, blue jays, and cardinals. We found a few surprises while counting: a belted kingfisher, a hooded merganser (among the 800 geese and 200 mallards on one small pond), a great blue heron, and five eastern bluebirds. The heron, bluebirds, and kingfisher are surprising in that they are quite uncommon in this area at this time of year (i.e. generally expected to migrate further south), but a quick search of eBird shows that they are not unheard of (note that the data include my CBC checklists).

The Christmas Bird Count is a great opportunity for new or newer birders, because you can (and probably will) be placed on a team with more experienced birders. You meet new people, see some birds—possibly adding a species or ten to your life list—and participate in citizen science. Professional scientists alone couldn’t do these detailed counts in this many areas all at once. While in many areas the annual count may have happened already, some areas might be still have a count coming up, so check to see when your local circle does its count.

Of course, if the count already happened and you don’t want to wait for next year, you can always participate in eBird. eBird is a project of the Cornell Ornithology Laboratory, and is a huge database of population counts. Participants submit their lists (including counts of individuals) with time, date, location, and some other information. The database keeps track of your life list (and many other lists), and also can show you data from all the aggregated observations. Are you wondering what birds you might see when you go on vacation? You can check that county/area in eBird, and get a graph showing the relative abundance of different birds seen in that area over the course of a year. Looking for a particular species? A map tool can show you where they have been seen, and at a detailed zoom level will show the individual observations.

To date, there have been no eBird checklists from Heard Island, or the ocean near Heard Island. However, I intend to do what I can (and I may not be alone in birding Heard Island) to get a few lists for eBird when I am there in March and April.

Walking on Lava (Flows)

A cascade along the Split Rock River, in Split Rock State Park (Minnesota).  Cascade is 2-3 m tall, and the lava is cold enough to touch.  Image credit: Bill Mitchell (CC-BY).
A cascade along the Split Rock River, in Split Rock State Park (Minnesota). Cascade is 2-3 m tall, and the lava is cold enough to touch. Image credit: Bill Mitchell (CC-BY).

On a conference call some weeks ago, Nigel Jolly, captain of the RV Braveheart which will be taking the Heard Island expedition to Heard Island in March and April, 2016, told the expedition members that they will be expected to be in good physical shape for this expedition. Specifically, he reminded us that not only will we need to be able to walk around on the uneven and slippery ground, but that we will need to do so while carrying heavy things (potentially fragile and expensive, and generally needed for a successful expedition). In order to prepare ourselves, we are to get out and try walking around with heavy stuff on uneven ground.

Naturally, my first thought was that he just told me I needed to go backpacking on the north shore of Lake Superior. Don’t twist my arm too hard!

I called my cousin, who I figured would also probably need some arm-twisting to go backpacking on the North Shore, and we figured out the logistics. We even managed to reserve a hike-in campsite in Split Rock State Park that was right along the shore. Before we left, I checked through Roadside Geology of Minnesota to see if there were any special features besides the anorthosite (rock almost exclusively made of the mineral anorthite, which is a feldspar) which makes up Split Rock itself, and I put a few places on the quick stop list for the drive home.

The geology along the Split Rock River did not disappoint. Here were lava flows, more than a billion years old (1 Ga). Along the river channel, columnar jointing was often evident (see the far bank of the cascade and the far canyon wall above). Most of the lava flows were massive. The opposite canyon wall in the photograph shows columns 5–10 m tall, which would have formed in a single flow. That’s a lot of lava! While hiking along, I was on the lookout for ropey pahoehoe flow-tops, but did not find any that I recognized.

Lava flows found along the North Shore are generally part of the North Shore Volcanic Group, and have an age of roughly 1.1 Ga. They were formed as part of the Mid-Continent Rift system, and now dip gently (~20°) toward the lake. Many of the flows are basalts (low silica, high iron), although there are rhyolites (high silica, low iron) in the area (such as Iona’s Beach).

Mid-Continent Rift system.  Volcanic rocks are in the striped regions, while the dotted regions indicate sediments derived from those volcanic rocks.  Not all of these rocks are at the surface; much of the area in central and southern Minnesota, Iowa, Nebraska, and Kansas are overlain by younger sediments (e.g. glacial till, Paleozoic carbonates).  Image source: Nicholson et al., via USGS.
Mid-Continent Rift system. Volcanic rocks are in the striped regions, while the dotted regions indicate sediments derived from those volcanic rocks. Not all of these rocks are at the surface; much of the area in central and southern Minnesota, Iowa, Nebraska, and Kansas are overlain by younger sediments (e.g. glacial till, Paleozoic carbonates). Image source: Nicholson et al., via USGS.

It was fun to get to see some igneous rocks up close in outcrop (I live on a lot of glacial sediments, and the bedrock is Paleozoic sediments). The backpacking definitely demonstrated that more such activities are needed, because my legs were quite sore by the end of the hiking and the next few days. However, we did have a gorgeous view from the campsite! In the photo below, you can see the gentle dip of the lava flows toward the lake. Obviously, the weather we had on the North Shore (quite comfortable!) was much, much better than is expected for Heard Island. I had a great trip, and hope to head back up some time for more hiking adventures.

A clear morning on Lake Superior.  The lava flows making up the points further down the shore can be seen dipping gently toward the lake.  Image credit: Bill Mitchell (CC-BY).
A clear morning on Lake Superior. The lava flows making up the points further down the shore can be seen dipping gently toward the lake. Image credit: Bill Mitchell (CC-BY).

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Nicholson, S.W., Cannon, W.F., and Schulz, K.J., 1992, Metallogeny of the midcontinent rift system of North America: Precambrian Research, 58 (1-4), p. 355-386. DOI: 10.1016/0301-9268(92)90125-8