GLY2100C – Historical Geology is a 4-credit laboratory science course covering the history of Earth and of life on it: how the planet formed, how continents assembled and broke apart, how climate and sea level changed, and how the fossil record documents roughly four billion years of biological change. It is the companion to physical geology (GLY2010C), which covers materials and processes; this course covers time.
The intellectual core of the course is a method. Nobody watched the Appalachians form or the dinosaurs die. Historical geology reconstructs events that left no witnesses from evidence that survives — the order of rock layers, the fossils within them, the chemistry of ancient sediments, the magnetic orientation frozen into cooling lava. Students learn to reason from present-day processes to past events, which is the same inferential move used in forensics, cosmology, and evolutionary biology.
Content covers the principles of relative dating — superposition, original horizontality, cross-cutting relationships, inclusions, and unconformities; numerical dating — radiometric methods, half-lives, isotope systems, and their limits; the geologic time scale — its construction, divisions, and the events that define its boundaries; sedimentary rocks and stratigraphy — facies, correlation, and sequence stratigraphy; depositional environments — interpreting ancient settings from rock and sedimentary structures; plate tectonics through time — supercontinent cycles, orogenies, and paleogeography; paleoclimate — proxies, glaciations, and greenhouse and icehouse states; the fossil record — preservation, index fossils, biostratigraphy, and the nature of evolutionary evidence; Precambrian history — Earth's origin, the Great Oxidation Event, and early life; Paleozoic — the Cambrian radiation, colonization of land, and the end-Permian extinction; Mesozoic — the breakup of Pangaea, dinosaurs, and the end-Cretaceous extinction; Cenozoic — mammals, Pleistocene glaciation, and human origins; and mass extinctions as a recurring pattern.
The laboratory covers rock and fossil identification, geologic map and cross-section interpretation, correlation exercises, relative and absolute age problems, and usually a field trip.
Offered at approximately 8 Florida institutions.
Florida's geoscience employment is dominated by water — the Floridan Aquifer, springs, wells, and contamination — along with coastal processes, sinkhole and geotechnical investigation, and phosphate and aggregate mining. Professional Geologist (PG) licensure in Florida is administered by DBPR and required for certain work products; it requires a degree, experience, and examination.
Worth checking against your degree audit. GLY2100C is carried at 4 credits at the institutions that offer it, including the University of Florida and Seminole State College, reflecting three hours of lecture plus a substantial laboratory. Its companion course GLY2010C varies — 4 credits at some institutions (UF) and 3 at others (FAMU, and several state colleges) — which means a student who took a 3-credit physical geology may find the two-course sequence adds to 7 rather than 8 credits. That matters if a program specifies a credit total rather than course names. SCNS equivalency applies to the same number at the same level, never across numbers, and it guarantees the course transfers — not that the credit value matches. Verify before assuming.
A student could be forgiven for thinking Florida is the worst place in the country to study historical geology — no mountains, no exposed ancient bedrock, essentially no igneous or metamorphic rock at the surface. In fact the opposite is true for this course specifically, because Florida is a nearly pure sedimentary and paleontological setting.
The peninsula is a carbonate platform: limestone and dolomite deposited in shallow warm seas over roughly the last 65 million years, sitting on much older basement rock that once belonged to Africa — a fragment left behind when Pangaea rifted apart, which is a genuinely striking fact and a direct illustration of the course's plate tectonic material. Florida is also one of the richest vertebrate fossil regions in North America, with exceptional Miocene through Pleistocene records: mammoths, mastodons, giant ground sloths, saber-toothed cats, dire wolves, and abundant shark teeth including Otodus megalodon. Sea level change — central to the course — is written directly into the state's terraces and is not an abstraction here.
Practically useful, and students routinely do not know it. Florida requires a Fossil Permit from the Florida Museum of Natural History to collect vertebrate fossils on state lands and in state waters — including river bottoms, which is where most Florida fossil hunting happens. The permit is inexpensive, valid for a year, and requires reporting significant finds. Invertebrate fossils and shark teeth are exempt from the permit requirement, which is why beach and creek collecting of shark teeth is unrestricted. Collecting on federal land is generally prohibited without authorization, and private land requires the owner's permission. A student who learns this distinction has something directly usable.
The central conceptual hurdle. Human intuition handles years, decades, and with effort centuries; it does not handle 4.6 billion years. Students routinely produce answers off by two orders of magnitude without noticing anything wrong, because the numbers are all simply "huge."
The fix is scaling, and it is worth doing personally rather than only reading. Compress Earth's history into one calendar year: the planet forms January 1, the first life appears around late February, complex animals not until mid-November, dinosaurs are wiped out December 26, and all of recorded human history occupies the final few seconds before midnight. Building this scale yourself — on a timeline, a hallway, or a roll of paper — produces an intuition that reading the numbers does not. Most instructors assign a version of it; take it seriously rather than treating it as a warm-up.
A subtlety students often miss. The fossil record is not a random sample of past life: it heavily favors organisms with hard parts, those living where sediment accumulates (especially shallow marine settings), and times and places where rock survived and is now exposed. Soft-bodied organisms, terrestrial uplands, and whole intervals of erosion are underrepresented or absent. This is why an apparent "sudden appearance" in the record may reflect preservation or sampling rather than a real biological event, and why unconformities matter so much — the missing time is often longer than the time preserved. Students who internalize this read the record as evidence to be interpreted rather than as a film with a few frames missing.
A 4-credit C course means a substantial lab, and it typically ends in a practical exam at specimen and map stations. Identifying a brachiopod versus a bivalve, or reading a geologic map to produce a cross section, is a hands-on skill that cannot be acquired from notes the night before. Photograph specimens during lab where permitted, sketch rather than only observe, learn the diagnostic feature for each fossil group rather than the overall look, and use open lab hours. Map and cross section work in particular is a procedure — practice several before the exam and it becomes routine.
Most Florida sections include at least one, often to springs, quarries, phosphate mines, river sites, or coastal exposures. Trips may carry a fee and require a waiver, and they are consistently what students remember. Standing in an active quarry looking at 20 million years of shallow marine deposition does something that a diagram cannot.
Generated August 31, 2026 · Updated August 31, 2026