ONE OF THE PRIMARY GOALS OF NASA'S EXPLORATION OF THE TERRESTRIAL PLANETS AND CONSISTENT WITH THE SSW PROGRAM IS TO UNDERSTAND THE GEOLOGICAL PROCESSES THAT HAVE SHAPED THEIR SURFACES. THE STEEP WALLS OF CRATERS ON THE SURFACES OF THE MOON AND MARS COMMONLY HAVE BEEN INCISED BY STEEP BEDROCK ALCOVES CHUTES AND CHANNELS. ON MARS SOME OF THESE LANDFORMS HAVE BEEN OF INTENSE INTEREST DUE TO THEIR RESEMBLANCE TO WATER-CARVED GULLIES ON EARTH AND THEIR RELATIVE YOUTH POTENTIALLY INDICATING RECENT OR CURRENT AQUEOUS ACTIVITY ON MARS. DESPITE THEIR IMPORTANCE SIGNIFICANT UNCERTAINTY EXISTS IN QUANTITATIVE INTERPRETATION OF CHUTES AND GULLIES ON CRATER WALLS BECAUSE WE LACK A MECHANISTIC UNDERSTANDING OF THEIR FORMATION. UNLIKE LANDFORMS DEVELOPED BY WATER-RICH FLOWS THAT ARE COMMON TO EARTH MECHANISTIC MODELS FOR THE FORMATION OF BEDROCK LANDFORMS BY DRY GRANULAR FLOWS CURRENTLY DO NOT EXIST. THIS KNOWLEDGE GAP SIGNIFICANTLY LIMITS OUR ABILITY TO IDENTIFY DOMINANT PROCESSES THAT HAVE SHAPED THE SURFACES OF MARS AND THE MOON WHETHER WET OR DRY. WE AIM TO ADDRESS THIS KNOWLEDGE GAP THROUGH THE COMPLETION OF THREE GOALS AIMED AT QUANTIFYING THE BASIC MECHANICS OF GULLY FORMATION BY DRY GRAIN FLOWS THROUGH EROSION OF A STRONG SUBSTRATE. 1) WE WILL DEVELOP THEORY AND A NUMERICAL MODEL FOR GULLY FORMATION IN BEDROCK AND CEMENTED SEDIMENTS. WE INTEND TO BUILD ON PREVIOUS WORK BY COUPLING THEORIES FOR ROCK FALL AND DRY GRANULAR FLOW BEDROCK WEAR AND LANDSCAPE EVOLUTION TO DEVELOP A QUANTITATIVE MODEL THAT CAN BE USED TO ASSESS THE ORIGIN OF LANDFORMS ON THE MOON AND MARS. 2) WE WILL TEST THE MODEL AGAINST A SERIES OF PHYSICAL EXPERIMENTS ON GULLY FORMATION BY DRY GRANULAR FLOWS WITH COHESIVE AND NON-COHESIVE SUBSTRATES. USING A 5-M LONG CHUTE AND A SYNTHETIC BEDROCK SUBSTRATE WE WILL INVESTIGATE WHETHER DRY GRAIN FLOWS ALONE CAN CREATE ALCOVE AND CHANNEL MORPHOLOGIES. IF SO WE WILL TEST WHETHER THEY OCCUR OVER A CERTAIN RANGE OF BED SLOPES AND QUANTIFY THEIR MORPHOLOGIC ATTRIBUTES. PARTICLES OF DIFFERENT DENSITIES WILL BE USED TO EVALUATE THE EFFECT OF REDUCED GRAVITIES. 3) FINALLY WE WILL MAP AND ANALYZE LANDFORMS ON THE MOON AND MARS TO DEVELOP A SET OF QUANTITATIVE MORPHOLOGIC CRITERIA TO DISTINGUISH BEDROCK GULLIES FORMED BY DRY GRANULAR FLOWS. WE WILL GENERATE THE FIRST GLOBAL MAP OF DEBRIS CHUTES ON THE MOON WHICH LIKELY FORMED IN THE ABSENCE OF WATER THAT SHARE THE SIMILAR MORPHOLOGIES AS THOSE ON MARS (ALCOVE CHANNEL AND FAN). THE DATABASE WILL BE USED FOR TARGETED ANALYSIS OF LUNAR DEBRIS CHUTES USING DATA FROM THE NASA LUNAR RECONNAISSANCE ORBITER AND THE JAXA SELENE/KAGUYA SPACECRAFT. THESE DATA WILL BE COMPARED TO COMPARABLE TOPOGRAPHIC DATA OF GULLIES ON MARS USING MRO HIRISE STEREO TOPOGRAPHY. THE LANDFORMS WILL BE ASSESSED FOR THE POTENTIAL OF DRY EROSION BASED ON COMPARISON TO NUMERICAL MODELING AND EXPERIMENTAL RESULTS. CONSISTENT WITH THE SSW PROGRAM SCOPE RESULTS FROM THIS RESEARCH WILL FILL A FUNDAMENTAL VOID IN OUR BASIC UNDERSTANDING OF PLANETARY SURFACE PROCESSES WITH SIGNIFICANT IMPLICATIONS FOR UNRAVELING THE HISTORY OF LANDSCAPE EVOLUTION SURFACE WATER AND OTHER VOLATILES ON THE MOON MARS AND OTHER ROCKY PLANETS. SPECIFICALLY WE EXPECT TO PROVIDE A MECHANISTIC UNDERSTANDING FOR THE FORMATION OF GULLIES IN BEDROCK SUBSTRATES AND THEIR QUANTITATIVE INTERPRETATION AS A PALEO-ENVIRONMENTAL TOOL THROUGH COMPARATIVE PLANETOLOGY MODEL DEVELOPMENT AND ANALOG EXPERIMENTS. IN ADDITION THE PROPOSED RESEARCH IS RELEVANT TO RESEARCH OBJECTIVES IDENTIFIED BY THE MARS EXPLORATION PROGRAM ANALYSIS GROUP (MEPAG 2015) AND THE PLANETARY SCIENCE DECADAL SURVEY (2013- 2023) TO UNDERSTAND HOW PLANETARY SURFACES ARE MODIFIED BY GEOLOGICAL PROCESSES AND TO CHARACTERIZE HABITABLE ENVIRONMENTS AND TO OBJECTIVES DESCRIBED BY THE LUNAR EXPLORATION ANALYSIS GROUP (LEAG 2016) TO UNDERSTAND THE HISTORY AND EVOLUTION OF THE SURFACE OF THE MOON.