DESCRIPTION OF MAP UNITS ALLUVIUM Qa Alluvium (Holocene) - Unconsolidated silt, sand, cobbles, and small boulders along streams, floodplains, and alluvial plains. Sediments well to poorly stratified, commonly in fining-upward sequences as much as 20 ft (6 m) thick. Includes alluvial terraces and colluvial debris from adjacent slopes as much as 40 ft (12 m) above stream channel. Bedrock outcrops too small to portray are exposed locally Qac Coarse alluvium (Holocene) - Cobbles and large boulders of mostly massive metamorphosed sandstone and conglomerate along upper elevation streams and flood plains in the Blue Ridge highlands. Coarse alluvium may be transitional with boulder debris on slopes. Rounded and sub-rounded boulders were derived and reworked from debris and colluvial deposits DEBRIS FLOWS Qdf Debris flow scars and deposits (Holocene) - Debris flow scars, tracks, and deposits in the Blue Ridge highlands as the result of modern and historic storms with high rainfall. Scars at the head areas are underlain by mostly slate bedrock, but bedrock, minor rubble, and vegetation are in scars in hollows and chutes oriented down slope. Deposits consist of slabby boulders, cobbles, and finer rock fragments of fresh slate and metasandstone, minor soil, and vegetation including trees and shrubs. On lower slopes, scars in channels have deposits consisting of logs and rock rubble that form terraces as much as 30 ft (9 m) thick. Debris flow scars, tracks, and deposits of post-1900 to pre-1970, and post-1970 debris flows are usually free of vegetation (Schultz, 1999) KARST QTs Sinkholes (Holocene) - Solution depressions (sinkholes), and hummocky, karst topography consisting of clusters of sinkholes and bedrock pinnacles, and cave openings in areas underlain by carbonate bedrock. Sinkholes are common in the Tennessee Valley but are also found within the tectonic windows in the foothills of the western Blue Ridge of Tennessee. Sinkholes are developed in alluvial valleys, on mountaintops, and within debris fan deposits and fluvial terraces QTr Residuum (Holocene) - Pebbles, cobbles, and small boulders of sub-angular chert, quartz, and jasperoid in red clay and silty soil overlying carbonate bedrock units in the western foothills. Includes a mixture of gravel of quartzite and vein quartz, pellets of manganese and iron, sand, and deep-red silt in broad areas of the Tennessee Valley that may be old alluvium mixed with residuum (Neuman and Wilson, 1960) SLOPE DEPOSITS Qc Colluvium (Holocene and Pleistocene) - Boulder streams, boulder fields, and talus containing minor alluvium and debris. Boulder streams and boulder fields are chiefly Pleistocene in age, colluvium ranges from Pleistocene to Holocene. Deposits are clast-supported diamicton of angular to sub-rounded boulders and cobbles of quartz-rich rock. Sandstone and quartzite on Chilhowee Mountain, Tennessee, and metasandstone, metaconglomerate, quartzite, and gneiss in the Blue Ridge highlands form distinctly different colluvium that are not differentiated on the map. The Sandstone and quartzite on Chilhowee Mountain forms equidimension, 0.5m angular blocks of colluvium. Gneiss and quartzite form meter-long slabby blocks of colluvium. Metasandstone and metaconglomerate form a wider range of size of blocks of colluvium. The surface of the deposit is blocky and sparsely vegetated. Occur on higher slopes as talus near bedrock outcrop and escarpments, and as fill in steep hollows. Colluvium grades down slope and is transitional into debris. Thickness from 10 to 100 ft (3 to 30 m) Qd Metasandstone debris (Pleistocene) - Matrix-supported diamicton that form fans on lower slopes and valleys of the foothills of the western Blue Ridge in Tennessee. Consists of poorly-sorted sub-rounded boulders, cobbles, and pebbles of quartz-rich rock in a matrix of pebbles, sand, silt and clay that may be locally stratified. Fan-shaped deposits of metamorphosed sandstone and conglomerate of the Cades Sandstone and Walden Creek Group in the foothills of the western Blue Ridge, Tennessee, are vegetated with boulders on the surface Qdb Boulder debris (Pleistocene) - Matrix-supported diamicton that form fans on lower slopes and valleys in the Blue Ridge highlands. Consists of sub-rounded boulders, cobbles, and pebbles of massive metamorphosed conglomerate and sandstone of the Great Smoky Group. Matrix ranges from stratified to unstratified pebbles, sand, silt and clay. Fan deposits are vegetated with boulders on the surface. Thickness 10 to 100 ft (3 to 30 m) Qdbu Upper level fan of boulder debris (Pleistocene) - Matrix-supported diamicton of sub-rounded boulders, cobbles, and pebbles of metamorphosed conglomerate and sandstone of the Great Smoky Group that underlie a terrace as much as 120 ft (36 m) above adjacent boulder debris fans and alluvium near Cosby, TN, are remnants of an older debris fan Qdc Sandstone debris (Pleistocene) - Matrix-supported diamicton that form fans on Chilhowee Mountain, TN. Unconsolidated stony material consists of sub-rounded boulders, cobbles, and pebbles of sandstone and quartite of the Chilhowee Group supported in a red matrix of predominantly sand, with pebbles, silt and clay. Boulders and cobbles in the oxidized red and yellow matrix exposed in excavations have thick weathering rinds, are friable, and often weathered to saprolite. Surface of the deposits are vegetated with scattered sub-rounded boulders and cobbles. Thickness ranges from a thin veneer to as much as 40 ft (12 m). Fans are incised as much as 50 ft (15 m) by modern streams, and grade downslope to modern alluvium Qdcu Upper level fan of sandstone debris (Pleistocene) - Matrix-supported diamicton that form fans on Chilhowee Mountain, TN. Unconsolidated stony material consists of sub-rounded boulders, cobbles, and pebbles of sandstone and quartite of the Chilhowee Group supported in a rubified matrix of of predominantly sand, with pebbles, silt and clay. Boulders and cobbles in the oxidized red and yellow matrix exposed in excavations have thick weathering rinds, are friable, and often weathered to saprolite. Surface of the deposits are vegetated with scattered sub-rounded boulders and cobbles. Thickness ranges from a thin veneer to as much as 40 ft (12 m). Fans are incised as much as 80 ft (24 m) by lower fans of sandstone debris and are as much as 100 ft (30 m) above modern streams Qds Gneiss debris (Pleistocene) - Matrix-supported diamicton forms fans in areas underlain by Mesoproterozoic gneiss. Consists of slab-like boulders of gneiss in a matrix of predominantly sand, silt, and clay. Slabs of gneiss are parallel to their gneissic foliation and the slabs long axis generally is may be oriented parallel to slope Qdbl Boulder debris above carbonate bedrock (Pleistocene) - Matrix-supported diamicton forms bouldery fans on lower slopes of coves underlain by carbonate bedrock. Consists of sub-rounded boulders, cobbles, and pebbles of massive metamorphosed conglomerate and sandstone of the Great Smoky Group. Matrix consists of pebbles, sand, silt and clay. Thickness unknown; base may be modified by karst. Fan deposits are vegetated with grass fields and forests with boulders scattered on the surface Qdl Metasandstone debris above carbonate bedrock (Pleistocene) - Matrix-supported diamicton forms cobbly fans on slopes and valleys of coves underlain by carbonate rock in the foothills of the western Blue Ridge. Consists of sub-rounded boulders, cobbles, and pebbles of metasandstone and metasiltstone in a matrix of pebbles, sand, silt and clay that is locally stratified. Fan-shaped deposits are transitional down-slope to fluvial terraces and alluvial plains. Thickness unknown; base may be modified by karst. Fan deposits are vegetated with grass fields and forests with sparse boulders scattered on the surface Qdlu Upper level metasandstone debris above carbonate bedrock (Pleistocene) - Three fans of cobbly metasandstone debris in Tuckaleechee Cove, TN, are elevated as much as 80 ft (24 m) above adjacent fans of metasandstone debris, and represent a former erosion surface TERRACES Qt Terrace deposits (Holocene and Pleistocene) - Unconsolidated sand, gravel, cobbles, and boulders, mostly of quartz-rich rocks but also cobbles of metasiltstone, deposited by rivers along most major drainages. Deposits range from 0 to 30 ft (0 to 9 m) thick and are on terraces cut into bedrock. Terraces are as much as 30 ft (9 m) above present flood plain alluvium and some grade down-slope into alluvium. Deposits have been eroded from some terraces. Terraces shown in Cades Cove, Tuckaleechee Cove, and south of Cosby, are transitional with up slope debris deposits QTt Upper level terrace and deposits (Pleistocene) - Unconsolidated sand, gravel, cobbles, and boulders of quartz-rich rocks mostly deposited by rivers. Deposits largely have been eroded from terraces that are as much as 200 ft (60 m) above present flood plain alluvium. Elevated landform and deposit are from an old erosion surface. In Tuckaleechee Cove, upper level terrace may be transitional with metasandstone debris