GEOLOGIC MAP OF THE HARVARD LAKES 7.5' QUADRANGLE, PARK AND CHAFFEE COUNTIES, COLORADO By Karl S. Kellogg,1 Keenan Lee,2 Wayne R. Premo,1 amd Michael A. Cosca1 1 U.S. Geological Survey 2 Colorado School of Mines, Professor Emeritus 2013 Scientific Investigations Map 3267 ABSTRACT The Harvard Lakes 1:24,000-scale quadrangle spans the Arkansas River Valley in central Colorado, and includes the foothills of the Sawatch Range on the west and Mosquito Range on the east. The Arkansas River valley lies in the northern end of the Rio Grande rift and is structurally controlled by Oligocene and younger normal faults mostly along the west side of the valley. Five separate pediment surfaces were mapped, and distinctions were made between terraces formed by the Arkansas River and surfaces that formed from erosion and alluviation that emanated from the Sawatch Range. Three flood deposits containing boulders as long as 15 m were deposited from glacial breakouts just north of the quadrangle. Miocene and Pliocene basin-fill deposits of the Dry Union Formation are exposed beneath terrace or pediment deposits in several places. The southwestern part of the late Eocene Buffalo Peaks volcanic center, mostly andesitic breccias and flows and ash-flow tuffs, occupy the northeastern corner of the map. Dated Tertiary intrusive rocks include Late Cretaceous or early Paleocene hornblende gabbro and hornblende monzonite. Numerous rhyolite and dacite dikes of inferred early Tertiary or Late Cretaceous age also intrude the basement rocks. Basement rocks are predominantly Mesoproterozoic granites, and subordinately Paleoproterozoic biotite gneiss and granitic gneiss. DISCLAIMERS Although this information product, for the most part, is in the public domain, it also contains copyrighted material as noted in the text. Permission to reproduce copyrighted items for other than personal use must be secured from the copyright owner. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey. This database, identified as SIM 3267, has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review.Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty, expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute such warranty. The U.S.Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein. DATA FILES List of files: 00ReadMe.txt SIM3267_map.pdf SIM3267.met SIM3267_pamphlet.pdf Datafiles directory HarvardLakes.gdb.zip Geology HarvardLakes_channels HarvardLakes_dikes HarvardLakes_geo HarvardLakes_labels HarvardLakes_landslides HarvardLakes_lines HarvardLakes_pnts HarvardLakes_shd HarvardLakes_topo SIM3267_shapefiles.zip directory: HarvardLakes_channels.shp (dbf/prj/sbn/sbx/shp.xml/shx) HarvardLakes_dikes.shp (dbf/prj/sbn/sbx/shp.xml/shx) HarvardLakes_geo.shp (dbf/prj/sbn/sbx/shp.xml/shx) HarvardLakes_labels.shp (dbf/prj/sbn/sbx/shp.xml/shx) HarvardLakes_landslides.shp (dbf/prj/sbn/sbx/shp.xml/shx) HarvardLakes_lines.shp (dbf/prj/sbn/sbx/shp.xml/shx) HarvardLakes_pnts.shp (dbf/prj/sbn/sbx/shp.xml/shx) HarvardLakes.shp (dbf/prj/sbn/sbx/shp.xml/shx) HOW TO OBTAIN THE DIGITAL FILES The digital files constituting the geologic map database of this report can be obtained via the Internet from the U.S. Geological Survey publications website. Go to the web page at http://pubs.usgs.gov/sim/3267/ or http://dx.doi.org/10.3133/sim3267 and follow the directions to download the files. The main product is a Portable Document Format (.pdf) map, which requires Adobe Acrobat for viewing, and from which paper copies may be printed. Acrobat software runs on a variety of systems, and is available for download free of charge from Adobe at http://www.adobe.com. ArcReader may be downloaded free of charge from http://www.esri.com/software/arcgis/arcreader/download.htm for viewing additional files included in this report.