A SEARCH FOR METEORITES IN WISCONSIN

by

Laurie Ann Holle, Russell Plummer, David C. Schlereth and Mark G. Strobel

(Harald Schenk - Advisor)

INTRODUCTION

In the late 1880's, a Sheboygan Falls farmer named John R. Kuhn heard a loud commotion coming from his field. When he went to investigate, he found that a large 'rock' had fallen from the sky. He had several neighbors help him drag the object out of the field. The Smithsonian Museum offered to test it for him. Mr. Kuhn decided to keep the object near his home. It was to be used as a headstone on his grave.

Photo by Harald Schenk

The object is currently found in the Sheboygan Falls cemetery. Close inspection makes it doubtful that it could be considered a meteorite.

Photo by Harald Schenk

Sporadic meteorites that land on the surface of the Earth are thought to come from the asteroid belt. They are formed by collision. Many will take millions of years before they reach the vicinity of the Earth.

PhotPhoto by Harald Schenk

Meteorites come in one of three types. These are STONY, IRON, and STONY-IRON. Of these three, 92% of all objects picked up when the observer 'sees' the object come down are of the stony type. These are called FALLS. In comparison, 66% of the objects detected by searching the ground after a long period of time are of the iron type. These are called FINDS. The difference between these two groups may be directly related to weathering that grinds the stony type down, while it leaves the irons to last longer.

A meteor passing through the atmosphere, and possibly surviving the event.

The largest supply of meteorites is currently being found in Antarctica. The huge ice sheets serve as repositories of objects from space. Among these, are a number of objects that appear to have come from the lunar surface. Antarctica also supplied us with several samples that arrived from the planet Mars. Is it possible that similar glaciers in Wisconsin captured meteorites in the distant past? Is it possible to locate some of the iron meteorites that may have been left behind?

A visitor from space survived the plunge through the atmosphere.

Colossal continental glaciers have altered Wisconsin's landscape many times during a series of glacial periods over at least the last one million years through four different Ice Ages. The most recent of these periods was the Wisconsin Glaciation. The latter lasted from about 80,000 years ago until about 12,000 years ago. In some places this ice was more than one mile in thickness. It may be possible that meteorites sank through this ice, and were deposited in some of the many Kames. These are conical hills made out of sand and stone deposits from streams that flowed down through funnel-shaped holes in the glacial ice.

MOULIN KAME in the KETTLE MORAINE

(looking SW)

Used with permission from Louis J Maher, Jr.

MOULIN KAME

(VIEW to EAST)

Used with permission from Louis J, Maher, Jr.

MOULIN KAME

(VIEW to NORTH)

Used with permission from Louis J. Maher, Jr.

RESULTS

Obviously the DNR would frown upon any students who decided to dig up a Kame with pick and shovel. An alternative is to contact local gravel companies. Since a Kame is composed of sand and stone deposits, some companies may have obtained permission to excavate these mounds. During the stone selection process, gravel must be separated from impurities. The different expansion coefficient of a piece of metal would not be suitable for construction purposes. As a result, various contractors may have tossed out old iron meteorites without realizing it.

We contacted two local gravel suppliers. The first contractor claimed that they do NOT separate metal objects. They had found a large piece of copper at one time. They would allow us to search along the edge of their pit with a metal locator.

The second contractor told us that they DO separate metal objects, but only when crushing material. They do NOT use a locator when excavating original stone.

As a result of this, we decided that looking for iron meteorites in kames would amount to looking for a needle in a haystack. The few meteorites that may have been trapped in the ice would be hard to locate.