Geology:
Pennsylvania's sedimentary rock formations represent almost all geologic periods and include shale, sandstone, limestone, and coal. Southeastern counties have metamorphc rocks, such as schist, gneiss, and marble, and igneous rocks such as diabase and granite. The rock in Centre Coutry dates from the Ordovician and Cambrian periods.
Physiography (from "A Natural History of Millbrook Marsh: A Wetland In An Urbanizing Setting", A Paper in Ecology by Cheryl Joy Lipton, August 1988, http://millbrook.centreconnect.org/CL-Thesis/4Chapter.html )
Centre County exists partly in the physiographic Ridge and Valley province and partly in the Allegheny Mountain section of the Appalachian Plateaus province. The dividing line between the two provinces is the Allegheny Front, along the north side of Bald Eagle Valley. Millbrook Marsh is located in the Appalachian Mountain section of the Ridge and Valley province, in Nittany Valley, not far from the Allegheny Front. The provinces are defined by the bedrock and formation processes and each varies with regard to wetland types and frequency (Westerfield 1959, Davis 1993). The Ridge and Valley province has valleys of limestone and ridges of more erosion resistant sandstone. The Nittany Valley, as the others of the province, is underlain with limestone bedrock.
The existence of wetlands depends upon a variety of contributing factors, which also determine the type of wetland and its corresponding plant and animal communities. K. Bushnell (1989) entertained the question "Are wetlands dependent on or independent of the underlying geology?" Impermeability of the underlying substrate is one instance that results in a wetland. Another is the impermeability of the wetland deposits themselves, in the case of some fens, for example, peat deposits (Novitzki, 1989.) The fen at Millbrook Marsh exists because of a combination of characteristics of the site, including hydrology and geology. The limestone bedrock beneath the soil leaches calcium as the spring water continuously passes through, resulting in calcareous or alkaline, permanently saturated conditions at the surface. Often there are high concentrations of magnesium as well as calcium in the soils of fens (Western Pennsylvania Conservancy 1995).
The bedrock underlying Millbrook Marsh is comprised of interbedded limestones and dolomites, and groundwater occurs along joints and fractures, bedding planes, and solution cavities. Joints and fractures result from the structural deformation while solution cavities are caused by the chemical actions of groundwater. Two well-developed fracture traces, important as controls of groundwater movement, were found in the Millbrook Marsh area and intense solutioning is suggested by the large Bathgate Spring near the Axemann-Nittany contact (Clark 1965). The solution and joint interconnections seem to be well developed, which probably indicates a groundwater level in Millbrook Marsh essentially at the level of the topography, rather than perched. Slab Cabin Run separates Bellefonte Dolomite and Axemann Limestone beds. Axemann Limestone occurs on the west side of Slab Cabin Run and is characterized by a dominance of either calcilutite or calcarenite. It is mottled and banded with dolomite. Both Thompson Spring and Bathgate Spring are located in this formation. The numerous springs at the fen also issue forth from the Axemann Limestone formation. East of Slab Cabin Run is Bellefonte Dolomite, with thin sandstone and limestone occurrences in some areas (Clark 1965).
There is a significant amount of relief, elevation ranging from 290 to 365 m (950 to 1200 ft), on the Nittany Valley floor. The elevation of Millbrook Marsh ranges from 288 m (946 ft) above sea level to 290 m (950 ft) in the marsh area but up to about 297 m (975 ft) where Millbrook land abuts the Mt. Nittany Expressway. There are deeper soils on fairly flat upland areas than on slopes. In addition, an integrated drainage network goes headward into the surrounding upland areas. This is descriptive of a fluvial landscape, although when combined with the limestone and sinkholes, it forms a karst topography. Karst topography on the fluvial landscape is known as a fluvio-karst area (Agronomy Series 64 1980).
This wetland holds a freshwater march and a calcareous fen. “Wetlands” is a broad term that includes marshes, fens, bogs, swamps, vernal pools, and more. The EPA has a great website that explains the differences in these wetlands at: http://www.epa.gov/owow/wetlands/
History and facts:
This area has been used perhaps as far back as 8000 B.C. as a source of food and water by Native Americans who were visiting the area to gather jasper from the nearby source for stone tools such as projectile points, drills and scrapes. The jasper source was located under Park Avenue in the area where Orchard Road meets it. Groups most likely camped along the streams and hunted, fished, and gathered herbs from the marsh while in the area.
By about A.D. l, at least some groups in this region cultivated some native plants, such as gourd and sunflower. A maize variety was planted by A.D. 1000, and maize became a more important food source over the next centuries, although people continued to hunt and gather as before. Instead of moving as often, however, it appears that groups established villages along major rivers and streams, like the Susquehanna West Branch and the lower part of Bald Eagle Creek.
Large pieces of jasper were no longer needed for making spear points after about A.D. 500, when the bow and arrow was adopted in this region. The presence of some arrow tips here indicates that people continued to come here, either to live seasonally or on hunting and gathering forays from villages or hamlets elsewhere.
During the A.D. 1600s the population in the region appears to have decreased significantly. The reasons for this decrease remain unclear. During the 1700s Indian groups from the east and the south, for example the Delaware and the Shawnee, moved through Central Pennsylvania on their way to safer areas. Some of them stayed in this region for varying periods. These Indians had adopted many European customs by them. Pennsylvania Indian groups divided their loyalties between the English and the French and later between the English and the Colonies during the wars of the 1700s. After the Revolutionary War almost all the Indians left the territory of Pennsylvania; many of them moved west, first to Ohio and later to Oklahoma.
Millbrook Marsh Nature Center has a 12 acre farm area and 50 acres of wetlands, including wet areas, three streams, and a network of boardwalks so visitors can visit the area without impacting the ecosystem.
There are many types of plants, insects, birds, and animals that can be viewed by visitors. As you walk, watch for deer, muskrats, fish, dragonflies, ducks, kingfishers, blue herons, songbirds, and more! It is especially fun to look at the mud near the stream for tracks of other animals.
- Waypoint: Chesapeake Bay sign - Used to say the Bay was too shallow to remove pollutants.
- Waypoint: Boardwalk beginning. N 40° 48.815 W 077° 50.220
- Waypoint: Observation building. N 40° 48.782 W 077° 50.07
To log this Earthcache:
- list in your log some of the animals that you saw or heard during your visit.
- Optional: Post a photo of you or your unit at the Observation Tower.
- Before logging this Earthcache as found, please send via email answers to the following questions:
a) What feature of the Chesapeake Bay limits its ability to dilute pollutants that drain into the Bay from its watershed?
b) What color is jasper?