er35a - Tertiary Uplands |
er35b - Floodplains and Low Terraces |
er35c - Pleistocene Fluvial Terraces |
er35d - Cretaceous Dissected Uplands |
er35g - Red River Bottomlands |
er35h - Blackland Prairie |
er36a - Athens Plateau |
er36b - Central Mountain Ranges |
er36c - Central Hills, Ridges, and Valleys |
er36d - Fourche Mountains |
er36e - Western Ouachitas |
er37a - Scattered High Ridges and Mountains |
er37b - Arkansas River Floodplain |
er37c - Arkansas Valley Hills |
er37d - Arkansas Valley Plains |
er38a - Upper Boston Mountains |
er38b - Lower Boston Mountains |
er39a - Springfield Plateau |
er39b - Dissected Springfield Plateau-Elk River Hills |
er39c - White River Hills | er39c - Central Plateau |
er39j - Black River Hills Border | er39j - Northern Holocene Meander Belts |
er73b - Northern Pleistocene Valley Trains | er73b - St. Francis Lowlands |
er73d - Northern Backswamps | er73d - Grand Prairie |
er73f - Western Lowlands Holocene Meander Belts | er73f - Western Lowlands Pleistocene Valley Trains |
er73h - Arkansas/Ouachita River Holocene Meander Belts | er73h - Arkansas/Ouachita River Backswamps |
er73j - Macon Ridge | er73j - Bluff Hills |