|WHAT IS TIME WALK? TIME WALK is a series
of 30-minute videos that looks at different aspects of the geology of
York and surrounding counties. The series began in 1995 with “Geology of
York County.” This video introduces the viewer to some of the key
geologic sites in the county and how geologists interpret the exposures
to gain additional information on the Earth’s history. This video was
made possible by Baker Refractories, Thomasville Stone & Lime Company,
York Building Products, Global Stone Pennroc, and Codorus Stone Company.
The second video, produced in 1996, “The Delta
Story”, deals with the famous slate resources once mined in the
southeastern corner of York County. Not only are the many quarries
fascinating, but the rich heritage that remains in the small community
is overwhelming. “Triassic Park” is the third of the series and is
adopted for mainly the children to recognize that dinosaurs did not live
far away, but right in their backyards. Thanks to our sponsors National
Ronald McDonald House Charities, Ronald McDonald House Charities of
Central Pennsylvania, Kreutz Creek Preservation Society, C. W. Kondor
Teleproductions, Jones Geological Services and Global Stone Pennroc.
WHY DINOSAURS: For many years, dinosaurs have been one of the most popular
science subjects talked about by today’s youth. All you have to do is walk through
major toy store and see the many dino toys and models available. More than this,
many presentations I do annually, I am amazed how many students know the names
popular species. When people think of dinosaur finds, they envision those mighty
like Tyrannosaurus rex or the Triceratops, which lived during the Cretaceous
(144 - 66 million years ago). These are the most famous dinosaurs that lived during
the end of
their existence during this period. Actually, what happened in the Earth’s history
the dinosaurs extinct is not completely known. Presently, it is believed by
many that a
comet or asteroid collision with the Earth causing a “dusty” atmosphere which killed
the vegetation. Since most dinosaurs were plant eaters, their food supply thus became
In any case, these dinosaurs like the Tyrannosaurus were near the end of a long
line of dinosaurs and reptilian animals that roamed the Earth during the Mesozoic
(245 - 66 mya). The dinosaurs that are discussed in this video are some of the
known of their clan living during the Late Triassic Period (220 - 200 mya).
WHAT IS THE TRIASSIC PERIOD?: The Triassic Period is one of eighteen time
spans during the Earth’s history. Basically, the periods are divided according
to the type
of life based on the fossil record. Remembering that the Earth is believed to
be about 4.6
billion years old, the oldest fossil (algae) only dates back to about 3.8 billion
This algae was found in Greenland. The Triassic Period ranges from 245 - 208
mya and is
the earliest third of what is known as the Mesozoic Era, a wide subdivision
of time. The
other two periods making up the Mesozoic Era is the Jurassic Period (208 - 144
and the Cretaceous Period (144-66 mya). The Mesozoic Era is nicknamed “The Age
THE TRIASSIC PERIOD IN YORK AND ADAMS
COUNTIES: It is obvious that Triassic-aged rocks must be found
in our area if the remains or evidence of the earliest dinosaurs known
have been found in southern Pennsylvania. The examination of a
Pennsylvania geologic map shows the region where these rocks are found
in western and northern Adams County, and northern York County. Matter
of fact, land features or political boundaries do not interrupt the
geology, these Triassic rocks pass through every county in southeastern
Pennsylvania. Again, ignoring political boundaries, these Triassic rocks
run northward from Pennsylvania through New Jersey, New York,
Connecticut, and Massachusetts, and southward into Maryland, Virginia,
North Carolina and South Carolina. In fact, these rocks have been also
seen in drill cores from South Carolina, Georgia and Alabama. Geologists
refer to these areas as Triassic Basins, since their origin seems to
point toward a basin type of deposit, and not running continuous the
entire length of the East Coast. Much can be said of the Triassic
Basins, but due to restraints on space here, the materials will only be
those needed to understand why the dinosaurs roamed this region.
From the composition and features seen in
the Triassic rocks and the fossil evidence, the Triassic Period was a
pretty exciting time to live in southeastern Pennsylvania. As mentioned
above, the Triassic rocks were deposited in basins. The basin which is
found in our area is known as the Gettysburg Basin, which extends from
near Harrisburg southward into Frederick, Maryland. It was during this
time period that the super continent, Pangaea, was beginning to split
apart into the world as we know today. The rifting that was occurring is
today marked by these Triassic Basins. It is believed that a “hot spot”,
a stationary column of magma originating from the mantle, was located
outside of New York City. As the magma came closer to the surface, the
“hot spot” began to split into a “Y”-shaped configuration. The northern
arm extended into Connecticut, the second arm came south into
Pennsylvania and Maryland, and the third arm extended eastward, which is
now called the Baltimore Canyon, off of the East Coast. As rifting
continued and the landmasses started to move apart, these basins became
deeper and accepted sediment.
Picture for a moment, the Everglades in southern Florida. Based on
paleomagnetic evidence, it is believed that York and Adams counties were
close to the latitude of southern Florida during the Triassic Period.
That means the climate was subtropical, with much vegetation,
meandering streams, oxbow lakes and abundant marshes. Rainfall was heavy
during this time, carrying sediment from weathered bedrock predominantly
from the south and southeast into this basin. Understanding the
principles of stream evolution by observing them today, geologists can
understand the drainage pattern during the Triassic Period, a principle
we call uniformitarianism. place Triassic map from Chrastina and Jones
(1989) here In York and Adams counties, two rock formations make up the
Triassic area. The oldest is the New Oxford Formation, which is located
in the southern half of the Gettysburg Basin. Named for its good
exposures in New Oxford, this formation consists of conglomerate, shale
and sandstone and is believed to be about 6,000 feet thick (Stose and
Jonas, 1939). The younger, overlying rock unit is the Gettysburg
Formation, named for its good exposures in the railroad cut near
Gettysburg. The formation is composed of sandstone, shale and
fanglomerate. Stose and Jonas (1939) calculated the thickness as 18,000
feet. Imagine 24,000 feet of sediment being washed into this basin over
a period of about 80 million years. As a result of the rifting, magma
intruding through the sedimentary rocks, cooled and formed diabase (an
igneous rock with a similar composition as basalt, but coarser-grained).
The large intrusions only occurred within the Gettysburg Formation, but
dikes of diabase can be found extending to the north and south of the
Triassic Basins into Paleozoic rocks. Devil’s Den on the Gettysburg
National Battlefield is one of the most famous diabase outcrops in
eastern United States. These intrusions are considered "earliest"
Jurassic in age (Froelich and Gottfried, 1999).
TRIASSIC DINOSAURS: It was on the East Coast of the United States where the
first Triassic dinosaurs were found. In 1802, twelve-year-old Pliney Moody was
a field on his father’s farm in South Hadley, Massachusetts, when he noticed
markings in one of the rocks. This find quickly raised the interest of both
the amateur and
professional collectors. Over time, geologists and collectors sought to make
a “new find”
with the Early Mesozoic dinosaurs. The richest source of dinosaur tracks in
the world is
still considered the Connecticut Valley (Weishampel and Young, 1996). Footprints
been found in every state from Connecticut southward into North Carolina.
PENNSYLVANIA FINDS: The earliest documented find in Pennsylvania occurred in
1878 at the LeCron’s Copper Mine, near Emigsville, York County. Edward Cope
described bones and named them Galtonia gibbidens. Mr. Wanner ( 1898) discussed
teeth and bone from the same locality. Elsewhere in Pennsylvania, and excluding
and Adams counties, the following sites and species have been reported (Weishampel
LOCALITY SPECIES FOUND
Schwenksville, Montgomery Co. Grallator, Gwynedd
Berks Co. Atreipus
Coopersburg, Lehigh Co. Grallator, Rutiodon, Archosaurus, Chirolherum,
Limerick, Berks Co. Grallator, Chirotherium, Archosaurus
Reading, Berks Co. Atreipus, Grallator, Apatopus,, Batrachopus,
Chirotherium, Gwyneddichnium, Rhynchosauroides
Sanatoga, Montgomery Co. Grallator
Graterford, Montgomery Co. Grallator, Atreipus,, Gwyneddichnium,,
Arcola, Montgomery Co. Atreipus
YORK AND ADAMS COUNTY SITES: Compared to the other
counties in southeastern Pennsylvania, York and Adams counties have the
highest combined number of dinosaur finds. It was the intention of
“Triassic Park” to visit most of the sites to give you a glimpse of the
locality. Following is a listing of each site, geologic formation,
species found and any notable comments. Numbers correspond to locations
on the York/Adams counties map.
1. LeCron’s Copper Mine - New Oxford Formation - Galtonia gibbidens
First described by Edward Cope in 1878, teeth and bones of this dinosaur were
only the earliest reports of dinosaurs in Pennsylvania, but remains today, the
only site in
the Gettysburg Basin where skeletal remains have been found. Similar specimens
identified in 1898 by Wanner from the same site. The materials were found in
of a vertical shaft where low-grade copper ore was being removed.
2. Zion’s View Site - New Oxford Formation - Rutiodon carolinensis and Buettneria
Dr. Robert Stahle discovered the site in 1909 and continued to collect specimens
between 1910 and 1912. Under the leadership of Donald Hoff, a second phase of
collecting took place in 1972 by The Pennsylvania State Museum. Specimens collected
Stahle and others are at the Academy of Natural Sciences in Philadelphia and
Princeton University Collection of Yale Peabody Museum, New Haven, Connecticut.
specimens collected by Hoff are curated at The State Museum in Harrisburg.
Probably considered the most significant site in Pennsylvania, the phytosaur
Rutiodon and a metoposaurid amphibian Buettneria are the highlighted species.
phytosaurs were an extinct group of crocodile-like reptiles and were up to
fifteen feet in
length. The metoposaurs were one of the last families of an extinct group of
amphibians. This animal resembled a salamander and were up to six feet long.
probably fish eaters. Skulls, teeth and other bone material were identified
View. Other fossils found here, which is dated as Late Triassic, include clam
unionid pelecypods, primitive bony fishes and vertebrate coprolites.
3. Little Conewago Creek Site - New Oxford Formation - phytosaur and fish
Wanner ( 1921) described this site near the confluence of the Little Conewago
Big Conewago Creeks. Reportedly, teeth and scales were identified here.
4. Yocumtown Quarry Site - Gettysburg Formation - Grallator and
These footprints were found in several sandstone blocks in a small quarry and
described by William Hickok and Bradford Willard (1933). The quarry is now located
beneath a housing development. These tracks were discovered in the summer of
J. Carroll Hayes who informed Dr. George H. Ashley, State Geologist. Hickok,
investigating the Triassic rocks 0f the New Cumberland area, independently discovered
these tracks several weeks later in the course of his fieldwork. Later, the
discovered by Hickok were found to be those previously found by Hayes.
Specimens were collected by Hickok, F. T. Moyer and M. N. Shaffner, of the
Pennsylvania Geologic Survey. Bradford Willard visited the site with Shaffner
collected additional specimens. The better specimens were mounted and displayed
Pennsylvania State Farm Show in Harrisburg in January, 1933. Specimens were
donated to The State Museum in Harrisburg. A specimen is also found today at
Pennsylvania State University’s Museum of Minerals in State College.
5. Goldsboro Quarry Site - Gettysburg Formation - Grallator and
The site was located in a small quarry dug into the side of a hill just west
Goldsboro Road. The footprints were found in 1889. The matrix is sandstone and
resembles the Yocumtown site. Quarry is still visible but is located on private
6. New Cumberland Roadcut - Gettysburg Formation - Grallator
Bradford Willard of the Pennsylvania Geologic Survey is credited for this find
1934 as a widening project for U. S. Route 111 near the Capital City Airport.
dinosaur track was found on a slab of red shale, along with mud cracks, raindrop
impressions, and the prints of plant stems.
7. Trostle’s Quarry - Gettysburg Formation - Atreipus,
Anchisauripus, Otozoum and reptilian tracks
These tracks were located in a limestone quarry along the Bermudian Creek in
1937 by Elmer R. Haile, Jr. Tracks are considered Late Triassic in age. Also
found in the
thinly-laminated siltsotnes, fine-grained sandstones or calcareous siltstone were primitive archosauruan reptile tracks known
asBrachychirotherium and Rhynchosauroides. Tracks are locally in the collection
of The State Museum in Harrisburg and the Mineral Museum of the Pennsylvania State
University in State College. In May, 198, Dr. Roger Cuffey of the Pennsylvania
University and the author visited the site, and collected a slab of siltstone thought to have
come from the fossil horizon. Dr. Cuffey believes that an unidentified print
was present in
that slab. Rock from this quarry was used to construct the stone bridges on
Gettysburg National Battlefield. One bridge located over Plum Creek near Big Roundtop, contains
that shows an Atreipus footprint along with mudcracks and ripple marks, and
other obscure footprints (Anchisauripus and Otozoum).
SO WHAT DOES THE FOSSIL EVIDENCE TELL US?
The Phytosaur and Metoposaur from Zions View have already been fairly
well described above. Both were predators, probably mainly on fish.
Based on the fossils at Zions View, some 2265 million years ago, we can
picture a margin of a lake, where clam shrimp, freshwater clams, and
fishes lived. The Rutiodon was the largest animals on the landscape
(Lucas and Sullivan, 1996).
The teeth of the Galtonia, like those found at the LeCron’s Copper Mine,
tell us that the animal was a small, primitive ornithischian. The teeth
were only 0.18 to 0.22 inch high and broad triangular in outline.
Another ornithischian dinosaur, Atreipus, is quite common in
southeastern Pennsylvania, found only as footprints. It is interesting
to note that the name “Atreipus” originated from a York City high-school
principle and discover of many footprints in York County, Atreus Wanner
(Weishampel and Young, 1996). These footprints have only been found from
about a ten million year period - a good index fossil for the Late
Triassic Period (Lucas and Sullivan, 1996). It should be noted here that
different names have been used to describe the same dinosaur over the
years (i.e., Grallator, Anchisauriopus, Eubrontes and others). Today,
all of these are known as Grallator.
The footprint of a small theropod dinosaurand, the most common foot
printer in the Triassic on the East Coast, Grallator, is very similar to
the foot print of the Atreipus. Scientists have closely studied the pad
pattern and have learned how to separate the tracks. Based on both the
front and rear prints, the size of these animals can be determined. The
Atreipus was less than 3.3 feet high at the hips. They must have been
mobile on all fours, although the size of the prints suggests that the
front legs were smaller than the rear legs.
Since hind prints have only been found of the Grallator, it appears that
these animals were hind-walkers (bipedal). Again, based on the footprint
size and stride, the Grallator was about seven to twenty feet long. It
was calculated by Robert E. Weems of the United State Geological Survey
in Reston, Virginia, that the Grallator moved at a pace of 7.8 to 9.8
miles an hour. The prey of the Grallator, appears to be Galtonia,
Atreipus, and their own, as well as insects, amphibians and lizards. The
Rutiodon appears to have been hunted by the theropods as well (Weishampel
and Young, 1996).
insert 3 foot track drawings here
Chrastina, Paul B., and Jones, Jeri L., 1989. Whispering Hills: Geology of York
Lancaster Counties, Pennsylvania. Matrix Publishing, Dillsburg, Pa.
Cope, E. D., 1878. On some saurians found in the Triassic of Pennsylvania, by
Wheatley. Proceedings of the American Philosophical Society, v. 17, p. 177.
Froelich, A. J., and Gottfried, David, 1999. Early Mesozoic - Igneous and contact
metamorphic rocks in The Geology of Pennsylvania, Charles H. Schultz, editor.
Pennsylvania Geological Survey and Pittsburgh Geological Society, Harrisburg,
Hickok, W. O., and Willard B., 1933. Dinosaur foot tracks near Yocumtown, York
County, Pennsylvania. Pennsylvania Academy of Sciences Proceedings, vol. 7,
Kochanov, W. E., and Sullivan, Robert M., 1994. Finding phytosaurs in Pennsylvania
The story of Stahle, Sinclair and Zions View. Pennsylvania Geology, vol. 25,
Lucas, Spencer G., and Sulivan, Robert M., 1996. Fossils provide a Pennsylvania
standard for part of Late Triassic time. Pennsylvania Geology, vol. 27, no.
4, p. 8-14.
Ryan, J. Donald, 1980. Triassic fossil reptile footprints near Coopersburg,
County, Pennsylvania. Pennsylvania Geology, vol. 11, no. 6, p. 2-4.
Stose, George W., and Jonas, Anna I., 1939. Geology and mineral resources of
County, Pennsylvania. Pennsylvania Geologic Survey, 4th series, County Report
Wanner A., 1889. The discovery of fossil tracks, algae, etc. in the Triassic
County, Pennsylvania. Pennsylvania Geologic Survey Annual Report for 1887, p.
________, 1921. Some faunal remains from the Trias of York County, Pennsylvania.
Proceedings of the Academy of Natural Sciences, Philadelphia, vol. 73, p. 25-37.
________, 1926. Some additional faunal remains from the Trias of York County,
Pennsylvania. Proceedings of the Academy of Natural Sciences, Philadelphia,
vol. 78, p.
Weishampel, David B., and Young, Luther, 1996. Dinosaurs of the East Coast.
John Hopkins University Press, Baltimore, Maryland.
Willard, B., 1934. Additional Triassic dinosaur tracks from Pennsylvania. Science,
vol. 80, no. 2064, p. 73-74.
Basalt - A dark-colored, fine-grained igneous rock formed from lava.
Mainly composed of plagioclase feldspar and dark colored minerals.
Conglomerate - A sedimentary rock composed of water-worn rounded pebbles
cemented together in a finer-grained groundmass.
Copper Ore - Rock containing copper minerals, i.e. native copper,
azurite, malachite, etc.
Coprolite - Petrified excrement; fossilized dung.
Cretaceous Period - A last period of geologic time
during the Mesozoic spanning from 144 - 65 million years ago.
Diabase - An igneous rock, generally medium-to-coarse-grained with its
composition similar to basalt. Formed inside the Earth from magma.
Dinosaur - A group of animals that existed during the Mesozoic Era, many
of which walked with an erect stance.
Fanglomerate - A sedimentary rock containing angular pebbles cemented
into a finer-grained groundmass.
Formation - A mappable body of rock of measurable thickness and areal
Geologic Map - A map showing the formations, rock types and structure of
a particular area.
Gettysburg Basin - One of numerous basins that were active during the
Triassic and Jurassic periods, extending from near Harrisburg southward
to Frederick, Maryland.
Hot Spot - A stationary column of magma intruding up through the crust
and believed to be the driving force for splitting apart landmasses.
Jurassic Period - A middle period of geologic time during the Mesozoic
Era existing from 200 - 145 million years ago.
Mesozoic Era - Meaning “Middle Life,” a wide division of time subdivided
into the Triassic, Jurassic and Cretaceous periods spanning from 245 -
65 million years ago. Also referred to as the “Age of the Dinosaurs.”
Metoposaur - TYpe of amphibian that resembled a giant
salamander. Mud Cracks - An irregular crack formed by the drying and
shrinkage of clay, silt or mud.
Ornithischian - Class of dinosaur having pelvises composed of 3 bones
with pubis pointing backwards and a fourth projecting forward. The
“Duck-Billed” dinosaur belongs to this class.
Paleomagnetic - The study of the direction and intensity of the Earth’s
magnetic field through geologic time.
Pangaea - Super continent proposed by Alfred Wegener with his theory of
continent drift that all of the continents were joined together
approximately 245 - 220 million years ago.
Phytosaur - A class of reptile, but that is crocodile-like and adapted
to life on land as well as water, developing nostrils on top of the head
enabling them to breathe largely submerged.
Raindrop Impressions - Small indention in sedimentary rocks created by
rain dropping into the mud prior to the rock’s lithification.
Sandstone - A sedimentary rock composed of sand-sized grains cemented
Shale - A sedimentary rock composed of clay-sized grains compacted
Stegosaurus - Known as the “plate lizard” and was about 20 feet long,
living during the Jurassic Period.
Theropod - A type of dinosaur that walked largely on his hind legs,
known as “beast footed.” All of the Triassic theropods were carnosaurs.
Triassic Basin - A lowlands area during the Triassic Period that saw
abundant sedimentation through heavy rainfall.
Triassic Period - The earliest period of geologic time during the
Mesozoic Era spanning from 250 - 200 million years ago.
Tyrannosaurus rex - The largest meat eating dinosaur known, living at
the end of the Mesozoic Era. The animal stood about 20-feet high and
Uniformitarianism - a principle of geology that states “Every process
occurring on Earth today, has been occurring on Earth for millions of
years.” Traditionally, referred to “The present is the key to the past.”
more details on the York County Parks programs, go to the website
Department of Parks & Recreation