The southwestern part of the county is notable for some of the highest mountains in Missouri, and for steep, beautiful valleys that are for the most part accessible only by foot. Perhaps the most impressive such valley is Cathedral Canyon, which is difficult to get to but provides a spectacular hike between the steep bluffs of Trackler and Glade Dotted Black Mountains A full list of Madison County hiking trails and scenic areas, and just as importantly, how to access them, can be found at Madison County Parks and Hiking Trails
By driving west from Fredericktown on Highway 72 and looking further west, one can witness a rare geological oddity: the fossilization not just of a plant or animal, but of an entire very ancient landscape. As viewed from that vantage point, the round-profile rhyolite and granite hills of the western side of Madison County resemble an archipelago of heavily weathered islands, with the shallow tree-filled valleys taking the place of shallow seas. The resemblance is not a coincidence. These particular hills are in fact fossil islands from the Precambrian period. Even more remarkably, the remnants of the shallow sea in which they once stood can still be seen in the form of sedimentary dolomite deposits that still lap up gently against the sides of the much harder igneous and metamorphic rocks of the hills.
The hills were originally islands that developed over an unimaginably long period of gradual erosion, during a geological period when change took place much more slowly than it does today. The islands were subsequently submerged under an ocean, and in time buried under several thousand feet of much softer dolomite deposits. When the Ozark Mountains plateau was later pushed upward again, possibly due to an intra-continental mantle plume that may also have been responsible for some of the abundant ore deposits of the region, the softer dolomite was weathered away to leave the original Precambrian islands largely intact. Since juniper prefers a more alkaline soil, it is sometimes possible to locate the margins of the ancient sea from a distance by looking for the distinctive light green color of junipers growing on the more alkaline oceanic dolomite deposits between the island hills.
Another remnant of the ancient sea can be found in road cuts along Highway 72, where one can find small, rounded granite boulders that once rolled off of the ancient islands and into shallow sea surrounding them. Unlike more familiar forms of granite, these boulders are so soft that it is often possible to peel onion-like layers from them using only one's hands. The softness of these unusual stones reflects the very slow pace of events in the ancient archipelago, since such deep surface-inward weathering requires that the original rounded granite rocks remain immobile and undisturbed over immense lengths of time. Our much more dynamic modern world breaks such soft layers from rocks long before they can accumulate, so that modern granite rocks age not by getting softer, but by getting smaller.
Also west of Fredericktown but still within Madison County is the Silver Mines Recreation Area, which is situated along a steep river gorge of the St. Francis River. This area contains the ruins of both a 1920s silver mine and a World War II era tungsten mine. Examples of the minerals that were once mined can still be found in the abundant tailings on the south side of the St. Francis River, just downstream of a now-breached stone dam. They consist of metallic-appearing sulfides such as sphalerite, arsenopyrite, and marcasite embedded in opaque veins of quartz. Careful searchers can also find crystals of wolframite, a tungsten ore that was mined briefly during World War II when access to other sources was cut off, and small grains of topaz, which caused the earlier silver miners of the area considerable economic grief by wearing out their diamond-tipped drills more quickly than anticipated. Both highly magnetic magnetite and slightly magnetic ilmenite (titanium ore) grains can be found be found in patches of black sands left along the beach of the main swimming area.
Fredericktown is located at (37.559436, -90.294533).
According to the United States Census Bureau, the city has a total area of 4.4 square miles (11.4 km²), of which, 4.3 square miles (11.1 km²) of it is land and 0.1 square miles (0.4 km²) of it (3.17%) is water.
There were 1,625 households out of which 28.6% had children under the age of 18 living with them, 45.8% were married couples living together, 12.7% had a female householder with no husband present, and 37.8% were non-families. 34.4% of all households were made up of individuals and 21.7% had someone living alone who was 65 years of age or older. The average household size was 2.28 and the average family size was 2.89.
In the city the population was spread out with 23.2% under the age of 18, 8.8% from 18 to 24, 24.1% from 25 to 44, 19.4% from 45 to 64, and 24.6% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 78.1 males. For every 100 females age 18 and over, there were 71.7 males.
The median income for a household in the city was $21,354, and the median income for a family was $27,149. Males had a median income of $27,593 versus $16,729 for females. The per capita income for the city was $13,512. About 17.4% of families and 22.3% of the population were below the poverty line, including 31.4% of those under age 18 and 14.1% of those age 65 or over.