Highway 20 Fun

Saying good-bye to the North Cascades was a lot harder than I'd imagined. Spending a month in the wilderness made me really appreciate America's preservation of many forests.  I learned so much (and looked at enough maps) in the few weeks I was there that I was able to name many of the bigger landmarks while looking out the window on our flight out of Washington, like the Columbia River, Route 2, and Lake Chelan.

We spent a good part of our last week in Washington studying the rocks around Highway 20, the northernmost road in the state.  There, we were looking primarily at the golden horn batholith, a pluton that weathers to a pretty golden color.  We came across a few stunning outcrops and clear contacts between the golden horn rock and a volcanic rock.  In the picture below on the left, you can see human-sized xenoliths, or pieces of the country rock, that fell into viscous magma.  The magma solidified before the xenoliths had time to melt, leaving clear and impressive boundaries between the two bodies. Chill margins of smaller crystals that solidified quicker than the rest of the magma are often found bordering the xenoliths. On the right is a much smaller boulder exhibiting the same characteristics that we found on a hike the next day.

Equally as interesting, miarolitic cavities cropped up occasionally as well.  Miarolitic cavities form when pockets of gas exist in a pluton near the surface of the earth (about 1 km or less). In the space, crystals have room to grow without many obstacles. See below a picture of a crystal about 3 cm long in a miarolitic cavity in a boulder at the base of the xenolith-filled wall, pictured first in this post.

Finally, the funniest part of our time on highway 20 was watching Mike and Yuem teetering on a log as they crossed a river where a bridge used to sit.  Pay attention to the notice on the log.

Emily Shorin

Mineralogy 101

     For some of us, this summer has been one of our first exposures to field geology, and sometimes it feels like a crash course in geology as we learn something new each day. Mike has been incredibly patient with us and we've been picking up some mineral identification skills.
     Biotite is one of the more common minerals that we've seen in the rocks we've been working with. It's a mineral in the mica group, meaning that it is a sheet silicate and grows in platy crystals. It is usually a dark brown or blackish spot in the rocks that we see and easy to pick out if we can spot the flaky crystals.
     Feldspars are another class of minerals that have been extremely common in our adventures. Plagioclase (a type of feldspar) is typically easy to identify because it is a clean, white, opaque mineral in the rock. Things start to get a little confusing though when we wonder whether there are two types of feldspars in the rock... Although K-spar is typically pink in color, it can also appear to be white or grey with a degree of translucency. So adding this to a rock that is already composed of minerals that are grey, white and black... Things can get a little confusing.
     Quartz is in almost every rock we've seen so far, and it's usually a colorless, greyish crystal. Sometimes it's tough to tell it apart from a grey feldspar, but we've learned that feldspars will usually have reflective crystal faces that glint in the sun while quartz crystals are more glassy and won't have the reflective faces.
     Some of the rocks we've looked at had hornblende crystals (dark, needle-like crystals in the amphibole mineral group) and we've even seen a few metamorphic garnets in rocks..
     It's been great getting firsthand experience in identifying minerals and rock types out in the field, and I'm sure that the three of us will be well-prepared for our upcoming geology classes.

Yuem Park, Judy Pu
     

Culinary Efficiency

As ObiWan Kenobi once said, "Use the Forks." Wise advice indeed, especially when Judy "Chopsticks" Pu is in your group. With total disregard for traditional camping culture, Judy soldiers on with a simple pair of chopsticks, eating oatmeal, porridge, spaghetti... All credit to her though - she has proven to us that no cuisine exists that cannot be handled with two sticks.

Speaking of cuisine, the Fantastic Four have discovered and achieved perfection in culinary efficiency. Through experience, it has been proven that boiling water with two or three basic ingredients is more than sufficient to keep the stomachs of four active geologists satisfied. Dining perfection was achieved when 'ramen and vegetables' was created.

But all facetiousness aside, we have managed to stay well fed and healthy without spending ludicrous amounts of money. And not only that, but the meals we make are all tasty too (minus a few blunders [Oriental Seasoning Mix from Hawaii]).

Some Tuff Work

After almost two weeks of looking at igneous rocks, which are formed by cooling magma, Mike decided to switch things up and look at a set of sedimentary rocks for a day.  Sedimentary rocks are important because they have the potential to record the environment at the surface of the Earth where they are deposited.  In our case, we were using an old thesis (McClincy, 1986) as a guide to find some volcanic tuffs.  Tuffs are formed from volcanic ash expelled during an eruption.  Dating these rocks could help put time constraints on the deposition of sediments in the area, and will help correlate their history with the history of some of the igneous rocks that we've been studying. 
We drove to an area of the North Cascades where McClincy had described tuffs and found some of the rocks in road cuts along the canyons in which they were mentioned.  This helped us get a sense of the type of rocks we were looking for.  We noted sediment sizes and textures. Then we set off for our real goal - to sample tuffs that were deposited during the right time period.  After bush whacking up a steep hillside for 300-400 feet of elevation and discovering a trail at the top, we spent the rest of the day looking for and sampling layers of flaggy sandstone with rhyolite clasts that fit the descriptions in McClincy's thesis. Hopefully the samples we took will be of similiar age to the igneous rocks we mapped during our first week.

The view from the top of the ridge where we searched for tuffs.

Emily Shorin

Strikes and Dips

     On our second day, we stopped at an amazing outcrop where we could see multiple dikes, which we learned were created when molten rock intrudes surrounding rock and then solidifies. Here, we could see that the intruding rock had a much finer grain size than the host rock and contained more biotite, a dark colored mineral that forms platy crystals.

Emily standing by one of the dikes in the area!

Mike notified the rest of us that there were huge dikes overhead as well.

     The dikes intrude the rock at certain angles and it's useful to record as much information as we can about their orientations. At this outcrop, we were able to practice taking a lot of strike and dip measurements with our Brunton compasses. Strike refers to the line at which the dike intersects with a horizontal plane, and dip is the angle from horizontal along which the dike intrudes. Using the right hand rule with your fingers pointing downhill along the dike, your thumb will point in the direction of the strike and your fingers align with the dip.



     The outcrop area was massive--we scurried around taking measurements and learning about rock compositions in the area from Mike. A hand lens is extremely useful in studying the minerals that compose a rock because you can see the crystals a bit more clearly than you could with your eye alone, and Mike likes to remind us that we should have our noses to the rock if we want to use our hand lenses effectively.

An overview of the outcrop area with Mike, Emily, and Yuem

Judy Pu

Washington Wildfires

With stories of bears and rattlesnakes and collapsing cliffs, the North Cascades aren't exactly a place many would consider safe. Out here though, these tales can seem like just that - stories.  But within hours of our arrival here, we were faced with a very real danger.  During one of our stops at a rock outcrop along Grade Creek Road, a ranger came barreling down the road in the same direction we were traveling and informed us of a 2,000 acre wildfire in a valley below the road.  The fire was "mostly under control" but after we drove a bit further, the smoke and scarred landscape were clearly evident.  In fact, much of the area we drove through was replete with statues of blackened evergreens.  The only plant life in these areas is low lying brush that grows back after the fires although the ground is often covered in ash.
A few days later, while on a backpacking trip through terrain in the area of 6000 feet of elevation, we spotted smoke billowing in the direction of the Columbia river.  We could not see the actual fire but the smoke grew quickly and spread thinly over the entire area.  It appeared that the fire was put out in a few hours but the sunset that evening was fairly hazy from the remnants of the fire.
Since the fires are commonplace, Washington takes some precautions. Firebreaks, or linear areas where trees are removed, are cut through the area to prevent fires from spreading across them.  Signs are hung noting the wildfire potential in different locations. Campfires must be tended to very carefully or simply not lit.
While wildfires once seemed like a tale to me, I now recognize them as a very real danger that can considerably hurt the environment. Pictures to come if I can find a cord to plug in my camera.

Emily Shorin

Uphill, Downhill, and a Bit of Rain

This weekend, Judy and I went on a hiking trip with a grad student, Erin Shea, to the White Mountains in New Hampshire. On Friday, we hiked 4.5 miles up the Stony Brook trail near Mount Moriah to the Imp Campground, which is just off the Appalachian trail. Since it was our first backpacking experience, Judy and I had a lot to learn.  Erin taught us everything from setting up and using the stove to how to pack our bags, which will all be useful when we go into the field in a few weeks.  Rain was in the forecast for Saturday so instead of backpacking the original loop we had planned, we left our tent set up at the campground and hiked along the Carter-Moriah trail for about 8-9 miles.  The view was gorgeous once we got on top of the ridge.

We hit the summit of Middle Carter Mountain, one of the forty-five 4,000 foot peaks in New Hampshire.  Throughout the day, we stopped and looked at the rocks and learned a bit of geology. In the picture below, we were looking at the quartz, which is grayish and on the left, and plagioclase which is white and cracked.

Here is a dike, which is an intrusion into the rock and can be identified by the differences in weathering from the surrounding rock.

It rained from the late afternoon and throughout the night, but this gave us a full camping experience. On Sunday, we hiked back down the Stony Brook trail tired but even more excited for our fieldwork in Washington, now that we had caught a glimpse of what lay ahead.

Emily Shorin