Reconnaissance of alluvial fans as potential sources of gravel aggregate, Santa Cruz River valley, Southeast Arizona

Processes of Terrace Formation on the Piedmont of the Santa Cruz River Valley During Quaternary Time, Green Valley-Tubac Area, Southeastern Arizona

“…3-24). Additional details of the method are given in Lindsey and Melick (2002) and Lindsey and others (2007).…”

“…8). For this report, new data (appendix A, tables A1-A5) were combined with data from an earlier study (Lindsey and Melick, 2002). Details of methods and data are given in appendix A.…”

“…Global Positioning System (GPS) locations are shown for the separate counts (table A1); data are given in tables A2-A6. Lithologic categories of Lindsey and Melick (2002) were followed with minor modification. Five pebble counts from earlier work (Lindsey and Melick, 2002) were recast because the lithologic categories differed slightly from this report; the recast counts are reported again here.…”

“…Lithologic categories of Lindsey and Melick (2002) were followed with minor modification. Five pebble counts from earlier work (Lindsey and Melick, 2002) were recast because the lithologic categories differed slightly from this report; the recast counts are reported again here. Pebble roundness was classified in categories A-E (angular to well-rounded) of Pettijohn (1975, his fig.…”

“…In ephemeral streams, a variety of fluid flows, ranging from debris flow to channel flow to sheet wash, can leave behind sand and gravel deposits ranging from poorly sorted and unstratified to well-sorted and stratified (Blair and McPherson, 1994;Costa, 1988;Lindsey and Melick, 2002). Cooler, wetter conditions than today may have prevailed in southeastern Arizona during late Pleistocene time (Davis, 1999;Thompson and others, 2003), allowing some piedmont streams to flow continuously.…”