Logging Tasks:
- Look around you. Which of the following evidences do you observe from your place that prove that you are "inside" a volcanic crater and that the hill in front of you is the eroded neck (diatreme) of that volcano? (choose two)
A. there is a ridge around (mostly to the south) that is higher than where I am
B. the soil seems poor quality near the top of the hill, indicating very hard erosion resistant rock, thus no real soil for plants.
C. exposed lava/pumic at GZ or on the hill
D. different trees and grass than in the area behind us on Hwy 23.
E.steep slope running perpendicular to the road indicates a very different rock, one much harder than the one at GZ, thus likely of Igenous orgin.
- What surprised you the most about viewing the "neck" (volcanic eroded diatreme) of this volcano?
- Examine rocks near your feet (gravel by the side of the road). If possible, find a piece of nepheline syenite (image attached to page). Compare it to known pieces of granite that you have observed. Does the luster of the nepheline (the white/gray) differ dramatically from quartz in granite? How? If you have a nail along, attempt to scratch it with a nail, knife, or other hard-metal object. Does it scratch? Do you think that this is harder/softer than a granite (think a granite countertop)
Description:
Beemer's Volcano, Rutan Hill, or Sussex Volcano are some of the names used to describe this now-extinct volcanic diatreme viewable from scenic hwy 519 in Sussex County NJ. Evolutionary theorists place the last eruption of Beemer's Volcano about 420 million years ago, though most creationists would place it much more recently. It is part of the Late Ordovician Beemerville Alkaline Complex. The volcano is popular among geologists for being a rare site where one can observe a scarce type of igneous rock known as nepheline syenite. This mineral is unusual, and is only found 1/2 dozen places in North America, and several small and distinct other places worldwide.
Diatreme @ Beemer's Volcano:
What you see is probably different than what you expected when you heard the term "diatreme" or "neck" of a volcano. So let me explain. The diatreme of a volcano is the hardest part of the volcano and is where the "volcanic stuff" would blow out from or spill out from. This means that when the plate shift again and the volcano goes dormat, the last gifts from deep within the earth are what cool and plug up the vent that once poured out destruction. Typically it will cool at a different rate (different crystal structure) and even have different components than earlier magma. Whereas ash or pumice will erode away rather quickly, and other magma might erode away over the years, necks tend to be MORE resistant to erosion, though not completely so. This hill has experienced a lot of erosion. Whereas the neck viewed in northern New Mexico is rather sharp and angular and still looks like a vent frozen in time, rain, wind, and sun have changed this diatreme dramatically. Hopefully you notice, however, that the area you are standing in has also been altered by time....in a much greater way than the diatreme.
Rutan hill:
When you view the highest point (the center of the neck) you are looking upward approximately 270 feet. The core of this neck is a single 90 in diameter "plug" made of the Nepheline syenite. I'm not sure who found THAT, but think how neat that would be to see! Maybe you can find a piece or two!
References:
"Rutan Hill." Wikipedia. Wikimedia Foundation, n.d. Web. 02 June 2015.
New Jersey: Driving at the Speed of Life. 2003. Rutgers Press. Amazon.com preview. Accessed 2 June 2015.
"New Jersey's Own Volcano." Atlas Obscura. Web. 02 June 2015.
"Geological Society of America Bulletin." Petrology and Geochemistry of the Beemerville Carbonatite–alkalic Rock Complex, New Jersey. N.p., n.d. Web. 02 June 2015.