Fisher Brothers built automobiles in Detroit from 1919 – 1983. Then in April of 1984 the facility was abandon and remains in ruins today. The facility is falling into ruins which liken a post-apocalyptic state. Including stunning stalactite’s and limestone calcification such as found in caves presumed to be millions of years old. -4,5

Cave-Like Formations in Just Decades

Published 09/2026

Stalactites and other mineral deposits do not necessarily require thousands or millions of years to form. Detroit’s abandoned Fisher Body Plant provides a striking modern example of substantial cave-like formations developing within a historically known period.

Fisher Body Plant No. 21 was built in Detroit in 1919 and manufactured automobile bodies for decades. General Motors ceased operations at the plant in 1984, although the building continued to see some industrial use afterward before being abandoned in the early 1990s.

Since then, deterioration of the enormous concrete structure has allowed rainwater and groundwater to penetrate its roof, floors, ceilings, and walls. The result is an eerie, almost post-apocalyptic interior. Trees and vegetation grow inside portions of the building, standing water covers some floors, and mineral deposits hang from ceilings like formations in a cave.

A Modern Laboratory for Mineral Deposition

As water moves through concrete, it can dissolve calcium-bearing compounds. When the water reaches an exposed surface, chemical reactions with carbon dioxide in the air can cause calcium carbonate to precipitate. Repeated dripping gradually leaves mineral deposits behind.

The result can be stalactite-like formations hanging from ceilings and corresponding deposits developing beneath them.

These formations are sometimes called concrete stalactites. Their chemistry and formation process are not identical in every respect to stalactites growing inside natural limestone caves. That distinction is important.

However, both demonstrate the same broader principle: mineral deposition can occur rapidly when the necessary water, dissolved minerals, and chemical conditions are present.

Size Does Not Provide a Clock

When we look at a large stalactite in a cave, it may be tempting to assume that its size automatically represents an enormous amount of time. But size alone cannot tell us its age.

A formation’s growth rate depends upon numerous variables, including:

• the amount and frequency of water flow,
• the concentration of dissolved minerals,
• the chemistry of the water,
• carbon dioxide concentrations,
• temperature and humidity,
• evaporation,
• and changes in these conditions through time.

Change those conditions and the rate of deposition can change as well.

This means that measuring a slow growth rate today does not by itself demonstrate that the same formation grew at precisely that rate throughout its entire history.

We Can Watch It Happen

This is what makes abandoned structures such as the Fisher Body plant especially interesting.

Unlike an ancient cave formation whose beginning was not observed, we have historical limits on the age of these man-made structures. We know when the buildings were constructed and approximately when they were abandoned and began seriously deteriorating.

Yet within that relatively short period, substantial mineral formations have developed.

This does not prove that every large stalactite in every natural cave formed rapidly. Different environments have different chemistry and growth rates.

But it demonstrates something equally important: a mineral formation cannot be assigned an age merely from its appearance or size.

The rate matters.

And the rate depends upon the conditions.

The Assumption of Constant Rates

This example also illustrates a broader problem when attempting to reconstruct the distant past.

Suppose a mineral formation is growing extremely slowly when scientists measure it today. If we take that present rate and extrapolate it backward, we can calculate a very old age. But that calculation necessarily depends upon assumptions about its previous growth conditions.

Those questions matter because a present rate is an observation, while extending that rate unchanged far into the unobserved past is an interpretation based upon assumptions.

The abandoned Detroit factory provides a useful reminder that favorable conditions can produce impressive mineral deposits on human timescales.

We therefore should be cautious about looking at a stalactite, stalagmite, or other mineral deposit and concluding from its size alone that vast periods of time must have been required.

The formation tells us that mineral deposition occurred. Its size alone does not tell us how long it took.

Sources

1. Michigan Department of Environment, Great Lakes, and Energy, information concerning the history and redevelopment of Fisher Body Plant No. 21.
2. Nailhed, The Night Shift, photographic documentation of abandoned Fisher Body facilities in Detroit.
3. Hill, C. A. and Forti, P., Cave Minerals of the World, National Speleological Society. Background on cave mineral formation and the environmental variables affecting mineral deposition.
4. https://www.nailhed.com/2014/06/the-night-shift.html
5. https://youtu.be/WYDYES0kt5I