Lab2 - Answers

23) Click here for the map
Click here for the relief/streams map
The geographic area is State College, PA
24) The general topography is Valley and Ridge (or something to that effect)
25) Name and Age of the oldest formation?
Nittany Dolomite - Ordovician Age, 443 - 490 million years old.
Just a reminder - the first letter of a symbol on a map stands for the geologic period in which the rock was formed. The second letter will denote the formation in some way. For example, St stands for the Silurian (S) aged, Tuscarora (t) Formation. The approximate ages for geologic periods can be found on your Geologic Time Scale p. xiv in the front of your lab manual
26) What is the name and age of the youngest formation?
Tuscarora Formation, Silurian Age, 417-443 million years old.
27, 28 SKIP 'EM
29)What formations form the hilltops? Why?
The Ridges in the area are formed by the Bald Eagle Formation, (Obe), the Juniata Formation, (Oj), and the Tuscarora Formation, (St). The Valleys are formed from the Reedsville Formation, (Or) through (everything in between) the Nittany Formation, On.
We haven't gone over rocks yet, so I'll keep it simple. The Stuff that forms ridges around here are Sandstones. The rocks that form valleys are Shales and Carbonates (Limestones and Dolomites). The basic idea is that sandstones are more resistant to weathering. So as time goes by, and all of these rocks are subjected to the elements, they wear away. However, the sandstones aren't worn away as much as the other rocks. So the sandstones 'stick out' more because they haven't been worn away as much. If you look at the last 2 pages of the packet we gave you, you will see the rock types of the area and the relief of the area. If you flip back and forth it should become obvious that the sandstones form ridges.
30See 29 above
31 Skipped
32) How does the geology affect....

1. Topography?
   It should be obvious that thhe ridges are Sanndstones and the valleys are mostly Carbonates (Limestone and Dolomite) and the ridges are Sandstones with Shale in between the two.
2. The location of streams?
   You should notice that the streams have a hard time getting through the ridges. Usually the streams start on a ridge and flow down and around them. It is rare for a stream to cut through a ridge. Where a stream cuts through a ridge is called a Water Gap.
3. Vegitation, orchards, farms, etc.
   This is a great area for farming (in case you couldn't tell!). The carbonate valleys produce fertile soil and gentle topography. Areas with ridges and sandy soils are usually covered with forests.
4. Location of communuties?
   The communities here form in the valleys. Notce that all of the major roads in the area run parallel to the ridges (NE-SW). This trend is a function of the geology. Towns that develop along these roads usually have the same trend. State College is one of those towns. When you travel "East or West" along College Avenue, you are actually traveling Northeast or Southwest. When you travel "North or South" along Atherton, you are traveling Northwest or Southeast! All because of the geology.....
   Another common place for roads is along streams and through water gaps. If you look at the relief/stream map this should be obvious to you.
5. Quarries and Mines?
   In years past, this area was mined for iron deposits. You may have noticed the centre furnace along college avenue ( click here for a history lesson) or the Martha Furnace along 220. These are old iron furnaces. The local forest were almost all cut at some point to become charcoal to fuel the furnaces.
   Current mining and quarrey operations are more concerned with Limestone. This area has the Valentine Member of the Benner Formation (note: The Benner formation is sometimes called the Lindon Hall Formation - as it is on your stratigraphy column). This limestone is very pure (almost all calcium carbonate, CaCO3). Indusutrial uses for this "high-calcium" limestone are pharmiceuticles, glass-making, cement and other industrial uses. Most of the operations in the area focus on the Valentine Member, but some will use the surrounding limestone as well. Graymont operates a quarry just east of here in Pleasant Gap.