Table 1. List of frequently-used symbols and abbreviations.

Symbol	Definition
GM	Granular Material
RFT	Resistive Force Theory
Re	Reynolds number. Ratio of inertial to viscous forces in a system.
$\theta$	angle between body segment tangent and average direction of motion
${\theta }_m$	average maximum $\theta$, attack angle
$\xi$	spatial frequency, number of waves on the body
$v_{CoM}$	center-of-mass velocity
$v_{seg}$	segment velocity (as if riding on the trunk)
${\omega }_{CoM}$	angular velocity about the center-of-mass
${\beta }_d$	granular drag angle
$v_d$	plate drag velocity
$z$	depth intrusion into GM, measured from the free surface
$\rho$	density of granular material
${\beta }_s$	snake body slip angle
${\sigma }_n$	component of granular stress normal to area element
${\sigma }_t$	component of granular stress tangential to area element
${\sigma }_n/{\sigma }_t$	anisotropy factor. Ratio of normal to tangential stress
μ	scale-GM friction coefficient
$L$	total body length
$L/w$	Aspect Ratio, snake body length divided by width at the widest point
$g$	gravitational constant = 9.81 ms-2
$s$	arclength along snake body midline measured from the head