Hall of Geology Opened to Public

News presents briefs about current and forthcoming programs, events, exhibits and activities of historical and cultural institutions in Pennsylvania.

Geology – The study of Earth and its history.

Approximately 9,000 square feet of display area have been devoted to this exciting subject on the third floor of the William Penn Memorial Museum.

Pennsylvania’s extensive geologic history and rich.mineral heritage are reflected by the many educational and attractive exhibits in the new Hall of Geology. The subject material is explained by the use of audio-visual systems, dioramas, graphics, models, backlighted transparencies, fossil and mineral displays. Many touch and open “you are there” exhibits bring the subject of geology alive to the viewer.

Geology, as one might imagine, concerns pure physical events that occur through time, as well as the evolution of life forms. The exhibits in the Hall of Geology give more space to ancient life than to physical history.

The first area of the Hall, “Space,” is located adjacent to the Planetarium and serves as a staging point for groups. This area features a large Earth globe with a cutout showing the Earth’s crust, mantle, and core. Illumination here is achieved by ultraviolet lighting techniques.

The second, or orientation, area of the Hall utilizes modular construction to interpret seven basic subject divisions of geology. Members of the Museum staff spent many long hours in the field collecting specimens and taking photographs for the seven orientation modules. Specimens, photographs, and models are keyed with graphics to provide a wealth of information for the layman and professional alike.

After grasping some of the basic fundamentals of geo¬≠logy, the visitor enters the largest section of the new Hall. This exhibit area has been designed as a “walk through time” which ends in the contemporary Mammal Hall of our modern period. Although the oldest known rocks were formed more than 3.6 billion years ago, only the last 550 million years of Earth’s history can be explained with any degree of accuracy. In retrospect, most of the exhibits in the Hall’s main section explain the last large segment of Earth’s history.

The fossil bearing rocks of each geologic period are noted to contain evidence of a distinct, but sometimes over­lapping, assemblage of life forms. Paleontologists, geologists who specialize in the study of fossils, have reconstructed past life forms through the study of fossil evidence.

The Hall’s “walk through time” features the ten geologic periods in addition to a small area devoted to the Precambrian Eras. The periods and their important life events are listed as follows beginning with the oldest period.

  • Cambrian: Animal life gains armor.
  • Ordovician: Sea life takes many forms.
  • Silurian: Corals crowd the shallow seas.
  • Devonian: Life takes to the land.
  • Carboniferous: Swampy forests cover the lowlands.
  • Permian: Life in crisis.
  • Triassic: Reptiles diversify.
  • Jurassic: Reptiles rule the Earth.
  • Cretaceous: Reptiles decline. Modern forests appear.
  • Cenozoic: Mammals inherit the Earth.

Although considerable space has been devoted to each geologic period, special emphasis is placed on the Pennsylvanian Epoch of the Carboniferous Period. A life-size, walk through the reconstruction of an ancient tropical rain forest illustrates what paleontologists think Pennsylvania looked like 295 million years ago during the Pennsylvanian Epoch. This was the age in which our commercial coals of today were in the early formative stage. The forest reconstruction features lifelike models of insects, fish, amphibians, and a reptile in addition to the plant replicas, a true habitat group. A sound story keyed to spotlights will explain the exhibit as visitors pass through the reconstruction.

The fourth section of the Hall of Geology is devoted strictly to the display of mineral and gem specimens. Eight large cases exhibit specimens collected from the more famous Pennsylvania mineral localities. This assemblage includes a portion of the collection of John S. Frankenfield of Chester County. Restful gallery seating is situated adjacent to the mineral displays.

The new Hall of Geology was opened to the public July 1, 1976. The Richard Rush Studio, Chicago, Illinois, was the contractor for this project.


Donald Hoff is curator of Earth Science.