http://www.dcnr.state.pa.us/
Is the home page. Click on Geology. Then Click on Digital Maps, Data, and GIS You can find topographic maps for the whole state at
http://www.dcnr.state.pa.us/topogeo/gismaps/topos.aspxTopographic maps are in NAD 83.
An interactive Quadrangle Index is found at
http://www.dcnr.state.pa.us/topogeo/map61/stbase.aspxhttp://www.dcnr.state.pa.us/topogeo/gismaps/digital.aspx
is other kinds of maps such as bedrock maps
http://www.dcnr.state.pa.us/topogeo/map1/bedmap.aspxAn Abode file of a geologic map of Pennsylvania can be found at
http://www.dcnr.state.pa.us/topogeo/maps/map7.pdf(Good resolution, but takes some time to download.)
Aerial photos can be downloaded here
ftp://www.pasda.psu.edu/pub/pasda/doq/
But I’ve been unsuccessful it’s larger than any free space I have. (38 MB)