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.