Mount Nittany’s Geology and Soils

Mount Nittany, a Penn State and Nittany Valley Treasure Millions of Years in the Making

Mount Nittany Across Time

About 300 to 220 million years ago movements of great plates of the earth’s crust brought the African Plate up against the North American Plate, pushing thick layers of sedimentary rock into great folds and forcing some slippage of this folded mass up and over the thinner sedimentary layers to the west. The heavily folded and fractured region has become the Ridge and Valley Province in which we are located.

The more level layers to the west form the Allegheny Plateau which slopes away to Lake Erie as the layers become thinner. At one time the land rose several thousand feet higher in our area than it does now. Over time the mild acid of rain water has dissolved away carbonate rocks, limestone and dolomite, creating valleys, and erosional processes have removed most of the remainder. Shales, siltstones and soft sandstones have been more rapidly removed than the harder sandstones which now form the ridge tops. Mount Nittany is capped by Oswego sandstone which is fairly hard but not as resistant as the Tuscarora quartzite which caps the Bald Eagle and Tussey ridges.

As softer rocks are removed from beneath this cap it breaks off as sandstone rocks which cover the weaker rocks on the slopes below the ridge. On the soil maps this covering is shown as rubble (Ru). Actually, the rubble indicated on the map is quite thin in our area and in my opinion the character of the underlying soils predominates (HTF and BID), controlling use.

Weathering in place by the sandstone cap on upper and convex slopes produces soils of the Hazelton Series which cover most of our Mountain. These are acid sandy soils that can be fairly deep on the level or rather thin on steep slopes where runoff is rapid. They drain quickly and don’t retain much available water. Leaching removes soluble minerals and these don’t precipitate in deeper layers of subsoil. Hazleton soils are further classified for purposes of use recommendations according to the rock content and slope. HSD – Hazleton extremely stony sandy loam, moderately steep, 8 to 25% slopes. HTF Hazleton-DeKalb association, very steep, 25 to 80% slopes. HhB- Hazleton channery sandy loam, 3 to 8% slopes; HhC 8 to 25% slopes. (Channery – more than 15 % small stones.) The Soil Conservation Service (SCS) recommends that these areas be used for woodland, wildlife and aesthetic purposes. However, reforestation is difficult because the survival of planted seedlings has been found to be low. I suspect the low water availability is the main problem, although we could also have a problem with browsing by the many deer. Competition by other plants is not likely to be a major problem, except in areas densely covered by bracken ferns. Suitability for hiking trails is given the lowest rating, severe – “costly soil reclamation, special design, intense maintenance, or a combination of these is required”. These soils are corrosive to concrete. American chestnuts are most common in the area with HhC soil.

Where the Hazleton soils have moved down slope and been deposited as alluvium (carried by water) or colluvium (moved by creep, landslide, animal action, tree throw, etc.) on middle or lower concave slopes they become the Laidig Series. These are moderately deep and well drained soils but they develop a fragipan (hardpan), a relatively impermeable laver in the subsoil where dissolved minerals precipitate and cement the sands and silts. LeD – Laidig extremely stony loam, 8 to 25% slopes. LDF – Laidig extremely stony loam, steep, 25 to 60% slopes. These acid sandy soils are rather similar to the Hazleton soils from which they are derived, but may have a little more available moisture and fertility. They are poorly suited for trails except where the slopes are least. Because of the hardpan, rainwater and snow meltwater tend to remain on the surface for a time on relatively level trails such as along the Lions Paw and Conservancy boundary above Markel’s Gap. At these times trail damage is extensive due to hikers walking on the less compacted ground at the sides of the trails and by bicycles and horses which cut in deeply. The survival of planted seedlings is found to be low, probably because these soil s become quite dry between rains. There are extensive areas of bracken fern which shades out seedlings.

Below the sands of the upper Mountain lies Reedsville shale, exposed at two old quarries and seen underfoot on the lower part of the White Trail up the Mountain. This weathers to form the Berks Series of soils which are strongly acid and rather thin. Permeability is rapid but available water capacity is low. BID- Berks very stony silt loam, 8 to 25% slopes. BMF – Berks and Weikert soils, steep, 25 to 60% slopes. Shallow. Best suited for woodland, wildlife habitat and esthetic uses. BID is a little less unsuitable for trails than the sandy soils and may offer a little better survival of planted seedlings. The BID areas are heavily forested now.

On the nutrient-poor dry sandy ridges and upper rubble lands the best adapted tree is chestnut oak. Mountain laurel often grows on rubble areas, but is not abundant on our lands where the rubble is thin. A little lower, other oaks and white pine are successful. Some other valuable trees that are suitable, especially on the Laidig soils, are tulip poplar, magnolia tree, white ash, basswood and sugar maple. White pines are abundant in a couple of local areas on the upper south slopes. More should be planted elsewhere. (I’ve planted a few but had almost total mortality.) Some hemlocks could be planted where there is enough moisture. I don’t favor using non-native species such as European Larch and Norway Spruce which the SCS recommends. Nor do I favor planting the recommended red pine or Virginia pine which don’t occur naturally in the area, or pitch or table mountain pines which are present as all four of these species will do poorly unless planted in recently burned over areas or old field situations where they can get full sun.

Planting for wildlife could include hawthorn, crabapple, hazelnut, dogwood, shadbush, mountain ash and also wild grapes and Virginia creeper in areas where these are absent. I’m not in favor of clear cutting and planting field crops for wildlife although this is currently being done by our neighbors to the east on Laidig soils.

—Tom Smyth, August 2001

Geological History

Penn Pilot, a project sponsored by the Pennsylvania Geological Survey, is an online library of digital historical aerial photography for the Commonwealth of Pennsylvania. Using the interactive map provided on this website, you can browse, view, and download thousands of photos covering the Commonwealth from 1937 to 1942 and 1967 to 1972.

The following images show Mt. Nittany through the years. Some notes:

To leave town in 1938 to the east you went out East College and followed Elmwood into Lemont, then left on Pike, before heading back up to Dale Summit. No road “over” the hill.
The 1957 image taken in May of that year clearly show a trail to the overlook that it now named in honor of Mike Lynch.
The Mt.Nittany_1971 image also shows beginnings of the Mounty Nittany Expressway.
To view the images full size, use the download link. Right-click (PC users) or Control-click (Mac users) and Save File As or Save Target As.