The Harrodsburg map that will be explored in this guidebook consists of 32 detailed geologic quadrangle maps. The index map on the right-hand margin of this map sheet shows the names of each of the detailed geologic quadrangles (for example, Alcorn Geologic Quadrangle) that we combined to make the Harrodsburg map. References for these geologic quadrangles are listed in the "References Cited" section of the map sheet.
What information is found on the Harrodsburg map? This map is a bedrock geologic map. Bedrock is the rock immediately beneath the soil and vegetation. The map has information about the various types of bedrock and faults found in the area. It also shows areas of sediment accumulation, usually along rivers and streams.
What are the fault lines shown on the map? When geologic stresses are applied to a rock, it may rupture. A fault occurs at the point where a rupture or crack has developed and the rocks have moved past each other. Faults are shown on the map as fault lines and the more significant faults are named on the map. The "U" or "D" symbol at a mapped fault line indicates which side of the fault moved "up" or "down" relative to the other side. The faults shown on this map were formed many millions of years ago.
How do I use the map to find out about the type of rock in the area in which I live? After locating the area in which you live on the map, note the color and the 2- to 4-letter designation for that color. Look for that color and letter combination under the "Description of Mapped Units" column to the right of the map. Next to the key you will see the name for the rock layer (usually a formation name), and next to that, a description of the rock in that layer. The colorful column on the left margin of the map sheet shows the relationships of the layers of rock to each other (overlying or underlying), the thickness ranges of the layers, and the geologic system for each layer (formation).
What do the rock descriptions mean? Many of the terms used in the "Description of Mapped Units" column are technical terms used by geologists. The definition of many of these words can be found in the glossary.
What is a geologic system? Geologic time is divided into systems or ages with terms such as Ordovician, Silurian, Devonian, and Mississippian. When referring to rocks in Kentucky, the system refers to the period in time when the rocks were still sediments and had been deposited. In the case of sedimentary rocks, typically younger rock layers overlay older layers. The Kentucky Geological Survey Web site at www.uky.edu/kgs has additional information on geologic time.
What is the regional setting of the area covered by the Harrodsburg map? Kentucky is divided into six major geologic regions (see Fig. Simplified geologic map of Kentucky). These regions are based on the geologic systems (see above) of the bedrock in that area. The regions have specific biologic, physiographic (landscapes), and economic characteristics that are dependant upon the geology of that region. Mineral resources, ground-water quality and availability, and engineering properties of a region also vary from one geologic region to the next. The Harrodsburg geologic map includes parts of the Bluegrass, Knobs, Pennyroyal, and Eastern Kentucky Coal Field geologic regions. The Kentucky Geological Survey Web site at www.uky.edu/kgs has a more thorough discussion of the characteristics of each region.
What else is on the map?
Geologic discussion-A column of text along the right-hand side of the map sheet contains general information about how the map was made, the geologic setting, economic geology (for example, mining, and oil and gas), and a section on surface- and ground-water conditions (hydrogeology).
Geologic cross section-A cross section at the bottom of the map sheet shows the nature of the rocks in the uppermost crust of the Earth (from the surface to a depth of 400 meters or 1,312 feet below sea level). The cross section coincides with a line marked on the map from the northwest corner to the southeastern part of the map. The section shows folds and faults in the rocks along this transect. The gentle upwarping of the crust seen in the middle of the section is the Cincinnati Arch.
What is the scale of the map? The "scale" of a map refers to the ratio between a distance on the paper map and its equivalent distance on land. The scale of this map is 1:100,000. For example, one inch on the map equals 100,000 inches in actual distance; or one centimeter on the map equals 100,000 centimeters (or 1,000 meters, or one kilometer) in real distance on land. For convenience, several bar scales in English and metric units are shown at the bottom of the map sheet.
Where can I find more information? This publication contains a CD-ROM with additional, more detailed information pertaining to this map. Additional information can be found at the KGS Web site. The Web address for this map is www.uky.edu/KGS/maps/harrodsburg.html. Information at the Web site will be updated periodically.
If your questions are still not answered, contact a geologist at the Kentucky Geological Survey. at (859) 257-5500.