Adirondack Geology: A SparkNote Equivalent

I’ve begun tonight’s reading with Geology of the Adirondack Mountains by James McLelland and Bruce Selleck.

Perhaps it was a mistake to begin my reading this way. It is already past midnight, and I’m just realizing how dense geology can be. McLelland and Selleck have produced a fairly thorough explanation for the shaping of the Adirondack landscape. Their writing is riddled with scholarly vocabulary, including a new unit of time, “Ma”, which signifies 1 million years, and scientific names for each phase and layer of Adirondack earth and rock. At this point, I have to be honest: I’m overwhelmed.

I’m the kind of person that needs to see the big picture before I delve into details. On the off chance that there’s someone else out there like me, I’m going to put together a condensed geographic history of the Adirondacks. Hopefully, in doing so, I too can get a general feel for the topic before digging deeper into the dialect of plate tectonics and glaciation patterns.

New York State’s Adirondack Park Agency actually provides a helpful overview of Adirondack geology. Their website gives a nice explanation which I will distill into a series of bullet points:

Landscape patterns:

-       The Adirondacks form a dome, 160 miles wide and 1 mile high – McLelland and Selleck describe this dome as “an egg with its major axis to the north.”

-       The mountains are made of ancient rocks which are more than 1,000 million year olds; however, the mountains emerged only ~5 million years ago.

-       Giant bodies of ice (glaciers) moved into the Adirondack region, picking up rocks as well as scraping  and smoothing the earth’s surface

-       The ice rounded the summits of mountains and deposited rocks all over the land as it melted

-       The rocks are called erratics (probably because their placement is somewhat erratic…)

-       These aforementioned glaciers were formed ~250 thousand years ago. The earth was slightly colder and snow did not completely melt in the summers.

-       The ice eventually became thousands of feet thick; the pressure of the ice softened layers of ice below, “causing it to flow like molasses.”

About Adirondack soil:

-       Adirondack soil is young (~10,000 years old)

-       Soil could only begin development once glaciers melted (unglaciated areas in US have older soil)

-       As with all soil, it is made up of rock particles, decayed organic matter, live organisms, and space for air + water

-       Soil is generally thin, sandy, acidic, and generally infertile and subject to drought

Anyway, hopefully this information can serve as a nice diving board for the litany of facts to come!

Source: "Geology of the Adirondack Park." Adirondack Park Geology. Adirondack Park Agency, n.d. Web. 29 Sept. 2014.

 P.S. Here's a nice picture that explains "Adirondack Uplift"