Monthly Archives: October 2014

Field Work — Island County, WA, Megabreccia

I’ve just returned from an 8-day trip to the state of Washington to serve as a field assistant to my colleague Brian Demet and participate in a class field-trip to observe some really cool geomorphology. The field work was primarily on Whidbey Island, a glacial-sediment island northwest of Seattle that has isostatically rebounded about 300 m since LGM. We also worked elsewhere in Island County during our trip.

An outcrop that Brian and I scouted had a large exposure of megabreccias. A breccia is a broadly defined rock type and is essentially a rock that is comprised of smaller angular clasts bound by a fine matrix. Breccias form in a wide variety of high-energy environments that produce similar but distinctly different rocks; the key similarity is proximal and high-energy deposition. Below is an example of a common-looking breccia.


a common-looking breccia rock. Angular clasts (white) are bound by a fine matrix (gray).

The outcrop that I show below is the exposure of a megabreccia (mega- means large scale) within the glacially-derived sediment that the Whidbey Island bluffs are comprised of. Part of Brian’s thesis will be putting this outcrop into a broader context and story, to try and better understand grounding zone wedge deposits under the Antarctic ice sheet — but that’s another post for another time!

The outcrop here is approximately 60 m wide, and 15-20 m tall.

megabreccia deposit within glacially-derived sediment

megabreccia deposit within glacially-derived sediment


post-processed image to highlight large angular clasts

Reddit data — When is it really too soon to retail Christmas?

About this time every year, people begin to complain about retail stores having Christmas themed displays and merchandise out. Well, speaking objectively, I think it is totally fair game for retail stores to shift to Christmas-mode, once people begin to think and talk about Christmas. Can Reddit post topics act as a proxy to determine when people begin to talk about Christmas? In each of the following plots, the black open circles represent a single day’s value, and the red line is a 7-point moving average designed to eliminate the weekly periodicity of Reddit posting.

posts with 'christmas' in titleWell it looks like the beginning of an increase in Christmas related posts occurs in the middle of October, with a substantial increase at the very end of November (just after Thanksgiving). Let’s dig a little deeper though. In the plot below, I’ve taken the same data and plotted them on a logged y-axis to highlight the variability.

log plot of xmas posts

From the above plot, it seems that the steady increase begins as early as the middle of September! Is a steady increase really enough to conclude that the conversation has begun though? Well I decided to take a look at the variation in the data to try and answer that.

xmas_nmlzdIn the above plot, the data has been normalized per day to a percent of total posts that have Christmas in the title. On December 25th, 16% of posts to Reddit included the word Christmas in the title (over 16,000 posts)! Now, I took the period from April 1 to Aug 15, and determined the mean and standard deviation. The horizontal black line represents the mean for this period, and the gray box is 2 standard deviation from the mean.

Taking 2 complete standard deviations from the mean to be a good indicator of significant change, the conversation about Christmas breaches this threshold right in the middle of September.

Now, you are probably thinking “Well these posts in September and October are probably just all people complaining about the early retailing of Christmas!” Well yes, you may be right. But hey, even if that’s the case, the retail companies are succeeding at getting you to talk about Christmas which means it is worth their time to put up the merchandise early, since you then buy more!


Just for fun, here are the conversation plots for some other holidays!


Manning and Favre: Career TD leaders

In honor of Peyton Manning becoming the second player in NFL history to throw more than 500 touchdown passes, I put together a little graphic to show how he compares to the other QB with more than 500, Brett Favre.


Regular season cumulative touchdown passes for Peyton Manning and Brett Favre.

Looks like Favre slowed at the end of his career, but Peyton has only accelerated in the last few seasons with the Broncos. I have no doubts he will overtake Favre and become the leader in the next month.

Data from The Football Database


UPDATE: After sharing to Reddit, I have made a few more plots, and I include them below.

smoothed raw touchdown per game count. Not really much trend besides maybe the recent high per game TD period for Manning

smoothed raw touchdown per game count. Not really much trend besides maybe the recent high per game TD period for Manning

cumulative interceptions for the two QBs

cumulative interceptions for the two QBs

Field work — Wax Lake Delta

I was recently a participant on a field excursion with a crew out of the University of Texas to the Wax Lake Delta where they have ongoing projects. We simply went out to build some platforms that the research group will later place some long-term monitoring equipment on. Below is a satellite image of the Wax Lake Delta.


The WLD is a really interesting location for study because it’s entire history is well documented. The US ACE created a canal for flood control from the Atchafalaya River (really the Wax Lake) to the Gulf of Mexico in 1942, and the entire delta has been built by rapid deposition since then. The delta is therefore the site of numerous delta formation and autogenic process studies.

Below are a few more pictures from the field work, including one of the platforms we built.


me working in the levees of the WLD, near one of the build sites.


one of the four platforms we built. The structure will support an array of data logging equipment and a car battery. Theoretically, the platform is above the 1-5 year flood stage. Each of the four corner poles are driven about 10 feet into the ground. The other two poles are spares and will be used when attaching the monitoring equipment.

periodic rain meant lots of rainbows. Taken from the boat we had for the duration of the work.

periodic rain meant lots of rainbows. Taken from the boat we had for the duration of the work.


Reddit data — Graduate School talk

This is the first post in a series I’ll be doing about posting on Reddit for 2013. The posts in this series search through every single post made to Reddit in 2013 — that’s over 50 GB worth of data, and over 39,000,000 posts!

For this post, I examined every post made to any subreddit for any word that related to graduate school (including law and medical school) for each day of 2013, in either the ‘title’ or the ‘self-text’. The key used for positive matches is at the end of this post.


posts made to Reddit with words relating to graduate school in 2013. 1 data point for each day, red line is 7 point moving-average.

Maybe not as telling as I had expected, there’s a ton of variance day to day and week to week, but the most obvious observation would be the spike in graduate school related comments in the month of April, following a consistent increase in posts in March. I would suggest this is probably due to the fact that this is the time of the year when a lot of acceptance decisions come out.

Normalizing the data against total posts for the day is not any more telling, the profile is stretched a bit in the y-direction. The 7 point moving-average is an attempt to remove the weekly periodicity of Reddit posting.

The key used was [‘grad school’, ‘graduate school’, “master’s”, ‘masters’, ‘ phd ‘, ‘ gre ‘, ‘letter of recommendation’, ‘letters of recommendation’, ‘doctorate’, ‘law school’, ‘med school’, ‘medical school’, ‘transcript’, ‘undergraduate gpa’, ‘undergrad gpa’]. There are of course more keywords that could have been used, but many have multiple implications, and this list was used as an attempt to minimize false positives.