Today we have a chance to explore outcrops in-depth with Jonathan Allen who shares his photos from Nova Scotia, Australia, the western U.S., and more.
What is your name and your background?
My name is Jonathan (Jon) Allen. I received my BA in geology-biology (with a minor in performing arts) from Colby College in Maine and my MS and PhD from the University of Nebraska-Lincoln. I've worked as a geologist for Chevron for the past 11 years having worked in Bakersfield, CA and Houston, TX. I'm now working as a senior development geologist with our Gulf of Mexico business unit in Covington, LA.
How did you become interested in geology?
I have always enjoyed science; however, I was never really introduced to geology as a science until college. I initially started out as pre-med. I can't remember exactly why I decided to take the intro geology course in the second semester of my first year, but I did, and I absolutely loved it. I loved how intuitive geology seemed to be versus some of the other sciences and how I much I connected with it. I grew up on a blueberry farm in Downeast Maine, so when we learned about the last glacial maximum and the associated geomorphic landforms, that was a huge moment for me. I could explain why there was this narrow ridge in our backyard (esker), what formed those weird holes (kettles), or why there were so many large boulders just scattered all around (glacial erratics), and it was all just so fascinating. I'm also a big fan of history, so combining that with science in order to tell the many stories of the earth has never gotten old for me.
Where did you do your first field work? What was your overall objective?
My first field work experience was for my undergraduate research project. It took place in Baxter State Park in north central Maine along the Trout Brook. We were re-evaluating the depositional environment of the Trout Valley Formation, a Devonian sedimentary succession that is host to some of the very first land plants. Despite my field notebook being a graveyard for hundreds of black flies, it was an incredible first and introductory experience to field work.
Joggins Fossil Cliffs
One of my favorite outcrops is actually a stretch of coastal exposures from Nova Scotia. This picture is from the Springhill Mines Fm. and is part of the Joggins Fossil Cliffs, a 15 km stretch of near continuous coastal exposures on the northerly arm of the Bay of Fundy. This series of outcrops records the thickest and most comprehensive record of Upper Carboniferous coal-bearing strata in the world. These outcrops are so valuable that the area was named a UNESCO World Heritage Site in 2008. Part of my doctoral dissertation focused on these outcrops and I was fortunate to be doing field work the summer of the World Heritage designation.
Snapper Point Formation
Another of my favorite outcrops is from the Permian Snapper Point Formation in New South Wales, Australia. The reason I love this outcrop is because it is an excellent reminder that almost anything has the potential to be preserved in the geologic record. The photo is of a shallow marine succession with a very interesting feature in the middle. This feature, which is an almost upside down trapezoid is mud-filled with very chaotic bedding on either side. It' interpreted as an ice keel turbate, a record of an iceberg plowing through the sediment on the ocean floor of Gondwanaland. The fact that such a process is preserved in the sedimentary record is still just wild to me. I love how you can continue to be amazed at what surprises the Earth has in store for us no matter how long you've been studying it.
Kern River Formation
This outcrop is from the Kern River Formation exposed along Alfred Harrell Highway in Bakersfield, CA. This is a fluvial succession displaying a series of coarse-grained channel sandstone units with multiple erosional boundaries. It's pretty standard as far as fluvial outcrops go. It's one of my favorites because just over a mile away is the Kern River Field, the fifth largest oilfield in the US, where the primary reservoir is the Kern River Formation. Being able to drive up and walk and observe the outcrops of the reservoir you're producing out of is extremely unique and incredibly helpful as a geologist.