# Alternative Text Description for USGS Geologic Units

## TABLE OF CONTENTS

- Map Overview
- Geographic Context
- Key Insights
- Visual Elements
- Symbol Guide
- Additional Information
- Data Context

## MAP OVERVIEW

This map displays the geologic units of Florida and adjacent portions of neighboring states, showing the distribution of different rock formations and sediment types that comprise the region's underlying geology. The map presents 35 distinct geologic units identified by the United States Geological Survey, ranging from ancient limestone formations to modern sediments and dune systems. This geologic mapping supports mineral resource assessments and geoenvironmental studies by documenting the spatial distribution of bedrock and surficial geology across the state.

## GEOGRAPHIC CONTEXT

The map covers the entire state of Florida, extending from the Florida panhandle in the northwest near Pensacola to the southern tip at Miami and the Florida Keys. Major cities labeled on the map include Jacksonville in the northeast, Tallahassee in the northern panhandle, Tampa and St. Petersburg on the west-central Gulf coast, Orlando in the central interior, and Miami in the southeast. The map also shows portions of adjacent states including southern Georgia and Alabama to the north, providing regional geologic context. The Gulf of America borders Florida to the west and south, while the Atlantic Ocean borders the east coast. Cape Coral is marked on the southwest coast near Fort Myers.

## KEY INSIGHTS

The map reveals distinct regional patterns in Florida's geology. The southern portion of the state, particularly the area around Miami and extending northward along both coasts, is dominated by younger limestone formations including Miami Limestone and Key Largo Limestone, reflecting the state's marine carbonate depositional history. The central and northern interior regions show a complex patchwork of various geologic formations, with the Hawthorn Group and its subdivisions occurring extensively throughout central Florida in scattered patches. Coastal areas display linear patterns of beach ridge sediments, dune systems, and recent sediments, particularly evident along the Atlantic coast and portions of the Gulf coast. The panhandle region shows different geologic units than the peninsula, with formations such as the Citronelle Formation and Alum Bluff Group appearing in the northwestern portion of the state. Undifferentiated sediments occupy significant portions of central and northern Florida, indicating areas of mixed or complexly interbedded deposits.

## VISUAL ELEMENTS

### USGS Geologic Units

This layer represents the compiled geologic mapping of Florida showing the distribution of bedrock formations and surficial sediment units across the state.

### Alluvium (pale peach/cream color)

**Appearance:**
Light peachy-cream colored areas

**Distribution:**
Scattered throughout the state, particularly in river valleys and low-lying areas in northern and central Florida

**Notable locations:**
Small patches near rivers and streams throughout the peninsula and panhandle

**Spatial patterns:**
Typically occurs in elongated or irregular patches associated with modern drainage systems

### Alum Bluff Group (coral/salmon pink color)

**Appearance:**
Bright coral or salmon pink colored areas

**Distribution:**
Appears in the Florida panhandle region

**Notable locations:**
Concentrated in the western panhandle near Pensacola and extending eastward

**Spatial patterns:**
Forms relatively large, continuous areas in the northwestern portion of the mapped region

### Anastasia Formation (dark olive green color)

**Appearance:**
Dark olive green colored areas

**Distribution:**
Occurs along portions of the Atlantic coast

**Notable locations:**
Visible in coastal areas near Jacksonville and other sections of the northeast coast

**Spatial patterns:**
Forms linear to irregular coastal zones reflecting its origin as a coastal depositional unit

### Avon Park Formation (dark gray-green color)

**Appearance:**
Dark gray-green colored areas

**Distribution:**
Limited occurrence in scattered locations

**Notable locations:**
Small patches in northern portions of the peninsula

**Spatial patterns:**
Occurs as isolated exposures where older formations reach the surface

### Beach Ridge and Dune (light purple/lavender color)

**Appearance:**
Light purple or lavender colored areas

**Distribution:**
Distributed along coastal zones, particularly prominent on the Atlantic coast

**Notable locations:**
Extensive development along the east coast from Jacksonville southward, with notable presence in the Palm Coast and Orlando areas extending inland

**Spatial patterns:**
Forms elongated parallel zones along coastlines reflecting beach ridge development and dune formation processes

### Chattahoochee Formation (beige/tan color)

**Appearance:**
Beige or tan colored areas

**Distribution:**
Located in the panhandle region

**Notable locations:**
Appears in patches in the northern panhandle

**Spatial patterns:**
Occurs as scattered outcrops among other formations in northwest Florida

### Citronelle Formation (bright turquoise/cyan color)

**Appearance:**
Bright turquoise or cyan colored areas

**Distribution:**
Prominent in the western panhandle

**Notable locations:**
Large continuous area west of Tallahassee near Pensacola, with a distinctive branching pattern reflecting ancient drainage systems

**Spatial patterns:**
Shows dendritic or branching patterns suggesting fluvial origin, forms one of the most visually distinctive units in the panhandle

### Cypresshead Formation (dark red-brown color)

**Appearance:**
Dark red-brown colored areas

**Distribution:**
Scattered occurrences in northern and central Florida

**Notable locations:**
Patches in the northern peninsula and panhandle regions

**Spatial patterns:**
Appears as isolated outcrops or small clusters

### Dunes (brick red color)

**Appearance:**
Brick red colored areas

**Distribution:**
Scattered coastal locations

**Notable locations:**
Small patches along both Gulf and Atlantic coastlines

**Spatial patterns:**
Typically forms small, irregular patches in coastal settings representing active or relict dune systems

### Hawthorn Group (dark navy blue color)

**Appearance:**
Dark navy blue colored areas

**Distribution:**
Widely distributed across central Florida

**Notable locations:**
Extensive patches throughout the central peninsula, with notable occurrences in the Tampa Bay area and central interior regions

**Spatial patterns:**
Forms an irregular patchwork throughout much of central Florida, representing one of the most widespread units

### Hawthorn Group, Arcadia Formation (medium olive-green color)

**Appearance:**
Medium olive-green colored areas

**Distribution:**
Scattered throughout central Florida

**Notable locations:**
Multiple patches in central and southern portions of the peninsula

**Spatial patterns:**
Occurs as isolated areas within the broader distribution of Hawthorn Group units

### Hawthorn Group, Arcadia Formation, Tampa Member (gray-green color)

**Appearance:**
Gray-green colored areas

**Distribution:**
Localized occurrences in west-central Florida

**Notable locations:**
Present in the Tampa Bay region

**Spatial patterns:**
Forms discrete patches representing a specific stratigraphic member within the Arcadia Formation

### Hawthorn Group, Coosawhatchie Formation (brown color)

**Appearance:**
Brown colored areas

**Distribution:**
Occurs in central Florida

**Notable locations:**
Patches in the central interior of the state

**Spatial patterns:**
Scattered distribution among other Hawthorn Group units

### Hawthorn Group, Coosawhatchie Formation, Charlton Member (darker brown color)

**Appearance:**
Darker brown colored areas

**Distribution:**
Limited occurrences in central Florida

**Notable locations:**
Small isolated patches in the interior peninsula

**Spatial patterns:**
Represents a specific member within the Coosawhatchie Formation with restricted spatial extent

### Hawthorn Group, Peace River Formation (medium green color)

**Appearance:**
Medium green colored areas

**Distribution:**
Widely distributed in central and southern Florida

**Notable locations:**
Extensive areas in the interior peninsula, including regions around and south of Tampa

**Spatial patterns:**
Forms large continuous and semi-continuous areas, representing one of the most extensive Hawthorn Group members

### Hawthorn Group, Peace River Formation, Bone Valley Member (light gray-green color)

**Appearance:**
Light gray-green colored areas

**Distribution:**
Located in west-central Florida

**Notable locations:**
Concentrated in the area east and northeast of Tampa

**Spatial patterns:**
Forms a relatively cohesive area in the phosphate-bearing region of central Florida

### Hawthorn Group, Statenville Formation (light gray color)

**Appearance:**
Light gray colored areas

**Distribution:**
Present in north-central Florida

**Notable locations:**
Patches in the northern peninsula and near the Georgia border

**Spatial patterns:**
Scattered occurrences representing the northernmost Hawthorn Group exposures

### Hawthorn Group, Torreya Formation (medium purple color)

**Appearance:**
Medium purple colored areas

**Distribution:**
Located in the panhandle region

**Notable locations:**
Appears in northern Florida near the state border

**Spatial patterns:**
Forms discrete patches in the northern portion of the mapped area

### Holocene Sediments (light purple/mauve color)

**Appearance:**
Light purple or mauve colored areas

**Distribution:**
Scattered throughout coastal and low-lying areas

**Notable locations:**
Coastal zones and river valleys throughout the state

**Spatial patterns:**
Represents recent sediment accumulation in various depositional environments

### Intracoastal Formation (teal/turquoise color)

**Appearance:**
Teal or turquoise colored areas

**Distribution:**
Limited coastal occurrences

**Notable locations:**
Small patches along coastal areas

**Spatial patterns:**
Associated with coastal and near-coastal depositional settings

### Jackson Bluff Formation (dark teal color)

**Appearance:**
Dark teal colored areas

**Distribution:**
Present in the panhandle

**Notable locations:**
Occurs in the northwestern portion of Florida

**Spatial patterns:**
Forms scattered patches in the panhandle region

### Key Largo Limestone (bright magenta/fuchsia color)

**Appearance:**
Bright magenta or fuchsia colored areas

**Distribution:**
Located in extreme southern Florida

**Notable locations:**
Prominent in the Miami area and extending southward toward the Florida Keys

**Spatial patterns:**
Forms a distinctive large area in southernmost Florida, representing ancient coral reef deposits

### Miami Limestone (light purple color)

**Appearance:**
Light purple colored areas

**Distribution:**
Located in southeastern Florida

**Notable locations:**
Surrounds and intermixes with Key Largo Limestone in the Miami metropolitan area

**Spatial patterns:**
Forms the bedrock foundation of the southeastern coastal region

### Miccosukee Formation (salmon pink color)

**Appearance:**
Salmon pink colored areas

**Distribution:**
Limited occurrence in northern Florida

**Notable locations:**
Small patches in the panhandle and northern peninsula

**Spatial patterns:**
Scattered isolated exposures

### Ocala Limestone (tan/beige color)

**Appearance:**
Tan or beige colored areas

**Distribution:**
Scattered throughout northern and central Florida

**Notable locations:**
Various patches in the interior and northern portions of the peninsula

**Spatial patterns:**
Forms irregular outcrops where this middle Eocene limestone is exposed at or near the surface

### Residuum on Eocene Sediments (dark gray-blue color)

**Appearance:**
Dark gray-blue colored areas

**Distribution:**
Limited distribution in northern Florida

**Notable locations:**
Small isolated areas in the northern portion of the state

**Spatial patterns:**
Represents weathered material developed on underlying Eocene deposits

### Residuum on Miocene Sediments (lavender/light purple color)

**Appearance:**
Lavender or light purple colored areas

**Distribution:**
Scattered in northern and central Florida

**Notable locations:**
Various patches throughout the interior regions

**Spatial patterns:**
Irregular distribution reflecting weathering of Miocene-age parent materials

### Residuum on Oligocene Sediments (dark green color)

**Appearance:**
Dark green colored areas

**Distribution:**
Scattered throughout central and southern Florida

**Notable locations:**
Multiple patches in the peninsula, particularly in areas south of Tampa and in interior regions

**Spatial patterns:**
Represents weathered products developed on Oligocene formations, showing irregular patchy distribution

### Reworked Cypresshead Sediments (olive-tan color)

**Appearance:**
Olive-tan colored areas

**Distribution:**
Limited occurrence in northern Florida

**Notable locations:**
Small patches in the northern portions of the state

**Spatial patterns:**
Represents reworked material derived from the Cypresshead Formation

### Shelly Sediments of Plio-Pleistocene Age (gray color)

**Appearance:**
Gray colored areas

**Distribution:**
Limited coastal occurrences

**Notable locations:**
Small patches in coastal zones

**Spatial patterns:**
Associated with shell-rich deposits from the Pliocene-Pleistocene transition

### St. Marks Formation (light lavender color)

**Appearance:**
Light lavender colored areas

**Distribution:**
Present in northern Florida

**Notable locations:**
Appears in the panhandle and northern peninsula regions

**Spatial patterns:**
Scattered patches representing exposures of this Oligocene limestone

### Suwannee Limestone (bright orange color)

**Appearance:**
Bright orange colored areas

**Distribution:**
Scattered in northern and north-central Florida

**Notable locations:**
Notable presence in the Big Bend region and northern interior areas

**Spatial patterns:**
Forms distinctive orange patches where this Oligocene limestone is exposed

### Suwannee Limestone, Marianna Limestone Undifferentiated (dark brown color)

**Appearance:**
Dark brown colored areas

**Distribution:**
Limited occurrence in northern Florida

**Notable locations:**
Small patches in the northern portion of the state

**Spatial patterns:**
Represents areas where these two limestone formations cannot be readily distinguished

### Tamiami Formation (bright green color)

**Appearance:**
Bright green colored areas

**Distribution:**
Extensive in southern Florida

**Notable locations:**
Large continuous area in southwestern Florida around Fort Myers and Cape Coral, extending into the interior

**Spatial patterns:**
Forms one of the most extensive and distinctive units in southern Florida, representing Pliocene marine and estuarine deposits

### Trail Ridge Sands (light peach color)

**Appearance:**
Light peach colored areas

**Distribution:**
Linear distribution in northeastern Florida

**Notable locations:**
Forms a distinctive north-south trending belt in the northeastern portion of the state

**Spatial patterns:**
Shows linear pattern representing an ancient beach ridge system, one of the most prominent topographic features in northeast Florida

### Undifferentiated Sediments (pale yellow/cream color)

**Appearance:**
Pale yellow or cream colored areas

**Distribution:**
Widely distributed throughout central, northern, and coastal Florida

**Notable locations:**
Extensive areas throughout the peninsula and panhandle, forming the most widespread map unit

**Spatial patterns:**
Covers large portions of the state where sediments have not been differentiated into specific formations, likely representing complex mixtures of various ages and types

## SYMBOL GUIDE

The legend displays 35 distinct geologic units represented by different colors:

- **Pale peach/cream:** Alluvium - modern stream and river deposits
- **Coral/salmon pink:** Alum Bluff Group - Miocene marine and marginal marine sediments
- **Dark olive green:** Anastasia Formation - Pleistocene coastal coquina deposits
- **Dark gray-green:** Avon Park Formation - middle Eocene limestone
- **Light purple/lavender:** Beach Ridge and Dune - Holocene to Pleistocene coastal deposits
- **Beige/tan:** Chattahoochee Formation - Miocene marine limestone
- **Bright turquoise/cyan:** Citronelle Formation - Pliocene fluvial deposits
- **Dark red-brown:** Cypresshead Formation - Pliocene to Pleistocene sand and clay
- **Brick red:** Dunes - modern to recent wind-deposited sand
- **Dark navy blue:** Hawthorn Group - Miocene phosphatic sediments (undifferentiated)
- **Medium olive-green:** Hawthorn Group, Arcadia Formation
- **Gray-green:** Hawthorn Group, Arcadia Formation, Tampa Member
- **Brown:** Hawthorn Group, Coosawhatchie Formation
- **Darker brown:** Hawthorn Group, Coosawhatchie Formation, Charlton Member
- **Medium green:** Hawthorn Group, Peace River Formation
- **Light gray-green:** Hawthorn Group, Peace River Formation, Bone Valley Member
- **Light gray:** Hawthorn Group, Statenville Formation
- **Medium purple:** Hawthorn Group, Torreya Formation
- **Light purple/mauve:** Holocene Sediments - modern deposits
- **Teal/turquoise:** Intracoastal Formation - Pleistocene coastal sediments
- **Dark teal:** Jackson Bluff Formation - Pliocene marine sediments
- **Bright magenta/fuchsia:** Key Largo Limestone - Pleistocene coral reef limestone
- **Light purple:** Miami Limestone - Pleistocene oolitic limestone
- **Salmon pink:** Miccosukee Formation - Miocene clay and sand
- **Tan/beige:** Ocala Limestone - upper Eocene limestone
- **Dark gray-blue:** Residuum on Eocene Sediments - weathered material
- **Lavender/light purple:** Residuum on Miocene Sediments - weathered material
- **Dark green:** Residuum on Oligocene Sediments - weathered material
- **Olive-tan:** Reworked Cypresshead Sediments - transported sediments
- **Gray:** Shelly Sediments of Plio-Pleistocene Age - shell-rich deposits
- **Light lavender:** St. Marks Formation - Oligocene limestone
- **Bright orange:** Suwannee Limestone - Oligocene limestone
- **Dark brown:** Suwannee Limestone, Marianna Limestone Undifferentiated
- **Bright green:** Tamiami Formation - Pliocene marine and estuarine deposits
- **Light peach:** Trail Ridge Sands - Pliocene beach ridge deposits
- **Pale yellow/cream:** Undifferentiated Sediments - mixed or unclassified deposits

## ADDITIONAL INFORMATION

This geologic map represents a compilation of state-level geologic mapping conducted at various scales, integrated into a consistent regional database. The map shows bedrock geology and surficial deposits, providing information about the Earth materials that underlie Florida's surface. Some units are differentiated to the formation level, while others are shown as broader groups or undifferentiated categories, reflecting varying levels of geologic knowledge and mapping detail across different regions. The Hawthorn Group, which contains economically important phosphate deposits, is subdivided into multiple formations and members in areas where detailed mapping has been completed. Coastal areas show various sediment types related to beach, dune, and marine processes, while interior areas display a mix of limestone formations and weathered sedimentary deposits. The map is designed to support regional-scale assessments and should be used accordingly, recognizing that local-scale features may not be represented at this compilation scale.

## DATA CONTEXT

**Data Source:**
The data comes from the USGS Mineral Resources Program's compilation of state geologic maps digitized from sources with original scales ranging from 1:100,000 to 1:1,000,000. The compilation integrates existing state-level geologic mapping into a national-scale database to support mineral resource and geoenvironmental assessments. Data source layer name: FLGEOLNAD_1983_HARN_Florida_GDL_Albers.

**Definition Query:**
No definition query or data filter has been applied; the map displays all geologic units present in the source dataset.

**Scale Information:**
This is a regional-scale compilation map appropriate for statewide or multi-state analysis. Given the source map scales of 1:100,000 to 1:1,000,000, the map is suitable for understanding regional geologic patterns but not for site-specific investigations or detailed local mapping.

**Coordinate System:**
The map uses the NAD 1983 HARN Florida GDL Albers projection (WKID 3087), an equal-area conic projection optimized for mapping the state of Florida.

**Time Period of Content:**
The map represents a compilation of geologic mapping conducted over multiple decades by various state geological surveys. The geologic units themselves represent rocks and sediments ranging in age from middle Eocene (approximately 40 million years ago) to modern Holocene deposits.

**Limitations:**
As a compilation from multiple source maps created at different times and scales, this dataset may show inconsistencies at state boundaries or between mapping projects. The level of detail and unit differentiation varies across the mapped area depending on the quality and detail of the original source maps. Some areas are mapped as undifferentiated sediments where more detailed stratigraphic information is not available. The map shows geologic units at or near the surface and may not represent subsurface geology. Users should consult original state geologic maps for more detailed local information.

**Map Coverage:**
The map covers the entire state of Florida, extending from approximately 24.5°N to 31°N latitude and 80°W to 87.5°W longitude. Small portions of southern Georgia and Alabama are included in the northern extent to provide regional context. The map includes the Florida mainland, the panhandle region, and the northern portion of the Florida Keys.

---

The alternative text description of this map was AI-generated and may contain inaccuracies.