Lake Nicaragua

     Lake Nicaragua is the 19th largest lake in the world, the largest in Central America. Formed from tectonic activity, the lake is connnected to the Carribean Sea through the San Juan River, even though the lake is much closer to the Pacific Ocean distance-wise. Because of its connection to the Carribean (and therefore the Atlantic), the city of Granada has been an important port. Between the 17th and 19th centuries, Granada was repeatedly attacked by pirates, of which a more detailed account is given here. Though it is a freshwater body, Lake Nicaragua is home to some fish that are usually found in saltwater environments, such as tarpon, sawfish, and even Bull sharks. The sharks in particular will move back and forth between the lake and the Carribean Sea via the San Juan River. A non-native fish, a species of tilapia, has also been introduced into the lake, which could potentially threaten the other, native species of fish already present.
     Lake Nicaragua has also been the site of volcanic activity, which created two main features in the lake. The first feature is the island Ometepe, the largest volcanic island within a freshwater lake in the world. There are still two volcanoes on this island: Maderas and Concepción. Maderas is inactive and is the smaller of the two, while Concepción is still active (last eruption ending as recent as 3/12/11). The second feature is the Solentiname Islands. This is a group of about 35 volcanic islands towards the southern end of Lake Nicaragua. These islands are home to archeological sites, a national monument, and a wildlife refuge; they are also becoming an increasingly popular tourist destination.
    
     The Google image below shows Lake Nicaragua with the main features highlighted.

Lab 5 - Ocmulgee Nat'l Monument

     For this lab the class visited Ocmulgee National Monument. We spent some time in the visitor center, walked through some of the surrounding park, and visited the mounds that are monument's main feature. In the visitor center we learned that the main reason Native Americans first settled in the area was because of Macon's location on the Fall Line. The Fall Line is a geographical feature that separates two different landscapes in the Eastern U.S.: the Piedmont and the Atlantic Coastal Plain. The Piedmont is characterized by rolling hills that begin the transition into the Appalachian Mts, which differs noticeably from the flat, lower land of the Coastal Plain. Living along the Fall Line meant that Native Americans would be able to reap the benefits of living in both geographical areas, specifically that they would be able to gather food from the different sources in each environment. Later, as cities began to emerge, Macon was founded because of its location on the Fall Line. A characteristic of the Fall Line is that most rivers that cross it are only navigable on the east side of Fall Line. Because of this fact, Macon became an important river port since it was the farthest point inland that could be navigated to on the Ocmulgee River.
     As part of out time in the park area (which was woods with trails), Dr. Rood took the class to a creek that was off the trail. Though it was at a low point, this creek had been able to carve out an impressive amount of material overtime. By viewing the opposite bank, we were able to see the different layers the composed the ground in the park area. The top layer, directly underneath the grass, was an organic soil formed from the decomposition of leaves, branches, etc. Underneath that, there was a mixture of soil, sand, and clay, with the amount of clay increasing the further you went down. This layer gave away to the underlying material composed of almost 100 percent clay, which made up the majority of the ravine walls as well as the creekbed itself. The clay was in a few different colors (light gray, yellow-orange, and red) because of different minerals in the clay, and there were several shallow depressions where pockets of non-clay material had been eroded away. These two things combined to give the creek a colorfully interesting appearance.

Blood Sugar and Negative Feedback

A negative feedback loop is a system that works to resist change within the system in order to stay at a steady state known as homeostasis. One of the examples of a negative feedback loop is the human body's regulation of blood sugar. When blood sugar levels rise, the hormone insulin is released. Insulin forces cells to absorb the glucose from the bloodstream and also causes glucose to be converted to a different compound. Both of these things cause the glucose level in the blood to fall back to its normal, steady state (homeostasis). Also, in the event that the blood sugar level should below the steady state, other hormones are released that cause the glucose level to rise back to homeostasis. Below is a graph that shows the body's response to a dramatic increase in the blood's glucose level.

Lab 4 Part 2 - Soil Orders of the World

The different soils of the world are classified into twelve types, or orders, which are:

• Gelisols
• Histosols
• Spodosols
• Andisols
• Oxisols
• Vertisols
• Aridisols
• Ultisols
• Alfisols
• Inceptisols
• Entisols

Besides the soil order discussed below, more information on all of these soil orders can be found at: Soil Taxonomy

Andisols -
Andisols are formed from volcanic material (mainly ash), and contain a large quantity of glassy material (also volcanic). Because they form only in volcanic environments, andisols are not very common. The photo below shows the worldwide distribution of andisols.

Andisols are usually young, very fertile soils that have unique physical properties including the capacity to hold a large of amount of water. Another interesting property is the andisols ability to retain more phosphorous than usual in the soil, making it unavaible to plants. Andisols are further divided up into eight sub-orders, which are listed and briefly described here. Because of their fertility, andisols often support intensive farming for crops such as coffee, tea, and fruit. A profile of an andisol is shown below with measurements.

Lab 4 Part 1 - Community Garden

For this last lab the class visited a community garden located behind Centenary United Methodist Church. We used a variety of things to analyze the soil including a split-spoon corer, sieves, and a soil composition chart with an associated dichotomous key. We also discussed various issues that arise with urban gardens, mainly relating to soil contamination from elements like lead. The split-spoon corer was used to obtain vertical samples of the soil to see the arrangement of the different layers. The dichotomous key for the general soil categories was used to analyze the topsoil layer, and then the soil composition chart was used to determine what percentage of the soil was clay, how much was sand, and how much was silt. A shovel-full of the soil, containing multiple layers, was also put into the sieves. Each sieve had a different grade mesh, and the sieves were stacked on top of each other in order with coarsest one on top and the finest on the bottom. The soil was poured into the top sieve and the stack was sealed and then shaken. When we opened the lid on the top sieve, it was discovered that the larger particles had stayed on top and smaller ones had continued to fall through the sieves until they could go no further. With the exception of some particles that stuck together because of moisture, this allowed us to separate the materials in the soil by size. A photo of sieves stacked up is shown below.

Lab 3 - 5 Trees

1.) Carya illinoinensis (Pecan) - This large decidous tree is a species of hickory native to North America and can live for over three hundred years.

2.) Cornus florida (Flowering Dogwood) - A small decidous tree native to eastern North America usually with small flowers and a hard, dense wood.

3.) Ginkgo Biloba (Ginkgo) - An ancient tree that has been widely cultivated and used for medicinal purposes. It is the only living member in its class.

4.) Magnolia grandiflora (Southern Magnolia) - A medium to large evergreen tree with a heavy, hard wood that is native to the SE United States.

5.) Quercus hemisphaerica (Laurel Oak) - A medium sized tree that is in the red oak section of the genus Quercus. Native to the southeastern portion of the U.S. and prefers sandy soils.

Lab 3 - 5 Shrubs

1.) Ligustrum japonicum (Japanese privet) - An evergreen sometimes grown as an ornamental shrub, the fruit of which has been used in herbal medicine.

2.) Ilex Opaca (American Holly) - A medium sized evergreen with sharp, pointed leaves that is native to the eastern U.S.

3.) Rhododendron atlanticum (Dwarf azalea) - One of many species of azaleas, this one is a decidous shrub native to the eastern United States.

4.) Camellia japonica (Japanese Camellia) - A shrub native to Japan but is also the state flower of Alabama.

5.) Ligustrum vulgare (Ligustrum) - Also called the Common Privet, this shrub is one of many species in the Ligustrum family. Its berries are poisonous to humans but are usually eaten by birds.