Re: Have there ever been any volcanoes in Alliance, Ohio?

Dustin:

To my knowledge, there have not been any volcanoes in your part of Ohio in 
the past few hundred million years. The most recent volcanic activity in 
the general vicinity of Ohio took place about 370 million years ago, when 
eruptions in the growing Appalachian mountains to the east deposited 
layers of volcanic ash across Ohio. I do not think any pumice would have 
been preserved in these layers for so long, if it ever existed, because 
pumice is very fragile.

Ohio is part of the North American craton. A craton is a large mass of 
continental crust and consists of a single tectonic plate. The North 
American craton is a rigid body tens of miles thick and thousands of miles 
across. Most volcanoes are found near the edges of tectonic plates. The 
west coast of the U.S. has active volcanoes, because there several plates 
forming the floor of the Pacific Ocean are being pushed under western 
North America.

In some unusual situations, wild things (in a geologic sense) can happen 
inside a craton. For instance, running up the Mississippi River valley is 
a buried zone of weakness in the rock where the craton almost split in two 
many millions of years ago. The famous New Madrid earthquake of 1811-12 
happened here. Yellowstone National Park is a place where there were once 
volcanoes, and there is still hot rock at depth that makes geysers and the 
like. This is a special place where the rock far beneath the surface has 
been heated. However, Ohio has been pretty quiet geologically, along with 
most of the rest of the interior of North America, for a long time. (I 
know you had a small earthquake recently, but that was the result of 
stresses much smaller than would be needed to allow a volcano to form 
there.)

As for the rock you found, I can think of several possibilities. Are you 
sure it is pumice? If it doesn't float in water, then it is probably not 
pumice. Are you sure it is a rock? Some kinds of slag can look a lot like 
rocks. If it really is pumice, I can only suggest that someone lost it and 
then you found it.

There is one last thing I should tell you. The State of Ohio has a 
geological survey, a state agency responsible for studying and promoting 
safe use of all of the geological resources in the state. They will be 
able to tell you a lot more about Ohio geology than I can. Here is the url 
of their web site:
 http://www.dnr.state.oh.us/odnr/geo_survey/index.html

If you have any further questions, please contact your state geological 
survey and they will be glad to help you.

Good luck!

David Kopaska-Merkel
Geological Survey of Alabama
PO Box 869999
Tuscaloosa AL 35486-6999
(205) 349-2852
FAX (205) 349-2852
www.gsa.state.al.us