DOQQ

A Digital Orthophoto Quarter-Quad map, also referred to as the DOQQ map, is a "digital raster image of an aerial photo mapped by the USGS, specifically a "quarter-quad," or the extent of one fourth of a 7.5-minute quadrangle, often used in GIS applications" (google define). The DOQQ map shown above is a one meter example Washington, DC.

http://seamless.usgs.gov/website/seamless/products/1mdoqq.jpg

DEM

A DEM map, also known as a Digital Elevation Model, is a digital file consisting of terrain elevations for ground positions at regularly-spaced horizontal intervals (google define). The above map is a great model or example for a DEM map. It summarizes the date found at the Hartnett study site, and the color/shading of the different levels of elevation makes the map alot easier to read and easier to distinguish (the different layers).

http://www.uwec.edu/runningl/350_2001/DEM.jpg

DLG

A digital line graph, commonly known as a DLG, "is digital vector data representing cartographic information. DLGs contain a wide variety of information depicting geographic features (for example, hypsography, hydrography, boundaries, roads, utility lines, etc) (http://oregonexplorer.info/craterlake/dlg.html). The above digital line graph displays cartogarphic information gathered at Lake tahoe.

http://tahoe.usgs.gov/images/4ds/dlg_zoom.gif

DRG

A digital raster graphics map, also known as a DRG map, consists of scanned images of U.S. Geological Survey topographic maps. These scanned image can be used to collect, review, and revise other digital data (http://images.google.com/imgres?imgurl=http://www.tceq.state.tx.us/assets/public/gis/images/drg.gif&imgrefurl=http://www.tceq.state.tx.us/gis/drg.html&usg=__qxjL45cP4iIaG2I7U_tRa1wO3Vs=&h=556&w=607&sz=97&hl=en&start=4&um=1&tbnid=XTr5fV2kfCeExM:&tbnh=125&tbnw=136&prev=/images%3Fq%3DDRG%2Bmap%26um%3D1%26hl%3Den%26rlz%3D1T4GPEA_enUS297US302%26sa%3DN).

http://www.tceq.state.tx.us/assets/public/gis/images/drg.gif

Isopleths

An isopleth is any line on a weather map connecting points with equal values of a particular atmospheric variable; temperature, dew point, etc (google definitions). The example of an isopleth map above shows the date found while researching the chloride ion wet deposition in 2003. This map seems to be a variation of an isopleth map because there is no visible line connecting points with equal values, the numerals are just listed next to their dots.

Isopachs

An isopach is a line on a map drawn through points of equal thickness of a designated unit (google definitions). The map above is a excellent example of an Isopach map, showing a debris-flow deposit in terms of centimeter thickness.

http://vulcan.wr.usgs.gov/Imgs/Gif/Projects/MassMovement/Flume_Sept01/flume_deposit_isopach_map.gif

Isohyets

An Isohyet is a line on a map connecting points that receive equal precipitation. The map shown above is an example of the isohyet map and displays data found while researching the mean annual rainfall is Tasmania.
http://soer.justice.tas.gov.au/2003/image/265/water%20quantity/m-ilw_quantity_rainfall-l.gif