[meteorite-list] Sutter's Mill Question… (Topographic Maps)

[Paul H.]

As given in “Sutter's Mill Question..” at:
http://six.pairlist.net/pipermail/meteorite-list/2012-May/084908.html
Dennis Miller asked:

“For my personal edification, what is the name of 
the USGA Quadrangle map you are using. I need
to start another strewn field map, with itty bitty 
dots, so far.

1. freewu2000 at yahoo.com replied:

“In Placerville I picked up 15 min topomaps named 
Coloma. Also Pilot Hill to the west for where the big 
one are speculated to be.”

and 2. Dennis Miller replied:

“Thanks for the map information. I did go to USGS and 
ordered Coloma and Pilot Hill topos. The Coloma 
(#328961) map is a 2012 aerial map.”

For GIS-minded people, free georeferenced 1:24,000
scale topographic map mosaic for all of El Dorado 
County, California can be downloaded from the USDA
Natural Resource Conservation Service Geospatial 
Datagateway at http://datagateway.nrcs.usda.gov/ .
For thedownloading the  to the “Order by County/Counties” at:
http://datagateway.nrcs.usda.gov/GDGOrder.aspx .

>From the above link a person can get free 1. Digital 
Raster Graphic Topographic Map County Mosaic by 
the NRCS, 2. and 2. high-resolution aerial imagery for
2009 and 2010. Both of these are georeferenced. 
Finally, National Elevation Dataset, 3-meter resolution,
is available for download.

Individual georeferenced digital raster topographic 
maps are available for free from the Cal-Atlas geospatial 
clearinghouse at http://atlas.ca.gov/download.html 
and the Cal-Atlas: Imagery Download Tool at
http://atlas.ca.gov/imagerySearch.html . For finding 
the topographic maps check /choose the DRG data 
layer in the "Download Tool" menu

Coloma 1:24,000 topographic map is “DRG O Series o38120g8.”

Pilot Hill 1:24,000 topographic map is “DRG O Series o38121g1.”

There is a choice of either collared (untrimmed) or 
collarless (trimmed) DRGs (Digital Raster Graphics)
for the topographic maps.

I have loaded the individual DRGs for my field areas 
into the company Ipad and used available apps to keep 
track of my location as a blue dot on the DRG base I 
moved around doing fieldwork. The same can be done 
with many GPS units or other portable electronics.

Best wishes,

Paul h.