Geologic Maps Understanding the world underneath is the first step in understanding the world around... Geologic maps provide information about Earth resources, hazards, and environments Resources: Minerals Ground-water aquifers Hazards: Faults and folds Polluting operations Environments: Plants that could live well in area Geologic maps are the primary source of information for various aspects of land-use planning

Color represents the kind and age of rock. Section of geological map from NC… Colors relate to Geological periods that represents the age of the rock. Occasionally time of rock period spans over periods: 2 Capital letters = span of periods) … small letter = type of rock

Each color represents a different geologic unit (volume of a certain kind of rock of a given age range. Ex. Sandstone at one age might be colored bright orange while at another age pail brown.

Geologic Maps (https://www.nature.nps.gov/geology/usgsnps/gmap/gmap2.html) Geologic maps from various areas differ but all have the following in common: 1. Colored areas and letter symbols = kind of rock unit (age and type) (Ks) = (Cretaceous Period / sandstone) 2. Depositional contact lines = where two different geologic units are in contact (all geological units are formed over, under, beside and through other geological units. When the original geologic unit is preserved between more recent periods. Cretaceous Period = 141 to 65 million years ago

Making a Geological Map Using Geological Time Chart Geological Time Charts = Geological periods (color coded) Note: Different charts reflecting use of differing datasets and methods of interpretation.

Geologic Unites of Wake Co. NC Pink Foliated to Massive Granitic Rock (Permian/Pennsylvanian) at surface, covers 2 % of this area Foliated to Massive Granitic Rock (270-320my) - megacrystic to equigranular. Butterwood Creek intrusive and Rocky Mount intrusive suite. Lithology: granite Light purple stripe Blue Biotite Gneiss and Schist (Cambrian/Late Proterozoic) at surface, covers 2 % of this area Biotite Gneiss and Schist - inequigranular, locally abundant potassic feldspar and garnet; interlayered and gradational with calc-silicate rock, sillimanite-mica schist, mica schist, and amphibolite. Contains small masses of granitic rock. Lithology: biotite gneiss; mica schist; amphibolite; calc-silicate rock; granite Injected Gneiss (Cambrian/Late Proterozoic) at surface, covers 2 % of this area Injected Gneiss - biotite gneiss and schist intruded by numerous sills and dikes of granite, pegmatite, and aplite; minor hornblende gneiss. Lithology: biotite gneiss; schist; granite; pegmatite; aplite; mafic gneiss Don’t worry about knowing rock types for now… coming later. Note “Rock Unit” names for age ie, Cambrian/Late Proterozoic) Geologic Unites of Wake Co. NC

Geological Maps all have: Addition of lines (faults, folds, strikes and dips) where geological units meet : show which way layers are tilted as will as likelihood of being present. Fault lines between two rock units Dashes = less certain Folds where bending and warping of rock unit Fault lines can also be within a rock unit

Fault Lines

Strike and Dip Symbols Three parts: Long line = horizontal Short line = Tilt in surface Number = Tilt in degrees from flat

Little Geology Vocabulary: Lithology = Study of rocks and their formation Intrusions = a body of igneous rock that has intruded the surrounding strata

Rocks, Minerals, and Elements Elements: group of same atom with unique properties. Minerals: crystal structure created from the formation of a collection of one or more elements: -- Inorganic -- naturally occurring -- definite chemical composition -- crystal structure Rocks: composed of one or more minerals

Elements:

Mineral: Halite Salt | Minerals Education Coalition Mineral search

http://minerals.usgs.gov/minerals/pubs/commodity/ USGS Mineral Information https://www.mineralseducationcoalition.org/minerals Minerals Education Coalition © Note Mineral commodities in NC: Gypsum, Industrial sand, Kaolin, Mica, Perlite, Phosphate, etc

Topographic Map Just to show a topographical geological map with color that represents elevation not geological features. Mount Mitchell is tallest mountain in NC