Index to Online Geologic Maps (1968)

Due to a large number of requests for geologic maps of Maryland, we present here an online version of the out-of-print 1968 Geologic Map of Maryland. The original map was printed at a scale of 1:250,000, or 4 miles to the inch. The map was nearly 6 feet wide and 4 feet high. Due to this large size, it is not possible to present the entire map on a single page of our web site. Therefore we have divided the map into counties and a geologic map of each county can be view on a single page. Some counties with complex geology have been further divided into sections for greater detail. Click on any area of those maps to see a closer view. Maps with details are marked with an asterisk *.

Please do not attempt to use these maps for GIS, scientific, legal or other mission-critical purposes.  They are out-of-date, cannot be georeferenced, and are too general for local or regional use.  These maps are to be used solely for historical and illustrative purposes only. 

Geologic Map of Maryland (1968) Index
To view a map click on a county in the index map below or the list to the right * indicates detailed views available for these counties	Allegany* Anne Arundel* Baltimore* Calvert* Caroline Carroll* Cecil* Charles Dorchester Frederick* Garrett* Harford* Howard* Kent Montgomery* Prince Georges* Queen Annes St. Marys Somerset Talbot Washington* Washington, D.C. Wicomico Worcester * These maps have been divided into smaller sections for better detail. Click on an area of the map to view these details.
Map Legends: Allegheny Plateau and Valley and Ridge Rocks of the South Mountain Anticlinorium and Frederick Valley Western Piedmont Metasedimentary Rocks (1) Eastern Piedmont Metasedimentary Rocks (1) Eastern Piedmont Plutonic Rocks Coastal Plain Rocks and Sediments
Other Diagrams from the 1968 Geologic Map of Maryland: These images require a large-format printer if you want to print them. They will not fit on an regular printer page. Geologic Cross Sections through the Appalachian and Piedmont Regions (1) Geologic Cross Sections through the Coastal Plain Stratigraphic and Facies Relationships in the Piedmont (1) Metamorphic Zones in the Piedmont (1) References for 1968 Geologic Maps Miscellaneous Geologic maps: Generalized Geologic Map of Maryland (suitable for printing on 8.5 by 11 paper on your own printer) Draft Physiographic Map of Maryland (2008) Physiographic Provinces and Subdivisions in Maryland (2001) Great Falls gold district geologic map (1953) in Montgomery County Geology of the Chesapeake and Ohio Canal National Historical Park and Potomac River Corridor (USGS) USGS' Maryland STATEMAP factsheet, showing current progress in geologic mapping (1) Please note the changes in the former "Wissahickon formation" nomenclature that are presented on the Eastern Piedmont Metasedimentary Rocks page.

If you need a more up-to-date map, or paper copies of individual Maryland counties, please see the on-line List of Publications for geologic and topographic maps of Maryland counties. The 1968 Geologic Map of Maryland is out of print and we no longer distribute that map.

Caution: These images were scanned from a paper copy of the out-of-print and outdated 1968 Geologic Map of Maryland. Due to the age of this map, these images do not necessarily represent an accurate interpretation of currently accepted geologic theory. Because the projection of the original map was distorted during reproduction, and the paper medium is not stable, these images do not meet any cartographic standards. Therefore geographic or Cartesian coordinates cannot be applied to these images, and georeferencing is not possible.

These images are for illustration purposes only. Do not use these documents for navigation, legal purposes, surveying, or anything else other than document illustrations. They were created only to illustrate our publications and are not accurate enough to be used for any other purposes. You may use them as illustrations only, and you must give proper credit to Maryland Geological Survey when using these maps.

A new edition of the Geologic Map of Maryland is in the planning stages but will not be available for some time. Hopefully this presentation will fill the gap for some kind of general geologic information about the state, even if it is neither up-to-date nor geographically accurate.

PLEASE NOTE: Although these maps have been formatted for use over the Internet, they are still large and may take some time to appear on your screen. Please have patience while the data is sent to your computer, especially if you have a slow Internet connection.

Please check back occasionally for additions and corrections to this online map series.