3-dimensional view of grain-size variations beneath Salinas Valley, CA

Example of a 3-D model of grain-size variations within basin fill beneath Salinas Valley, California. Grain-size variations affect how fast water can be transmitted in the subsurface, with clay (shades of blue) being the slowest to gravels (shades of brown) being the fastest. Circular columns denote grain-size variations interpreted from lithologic descriptions by water-well drillers. Vertical slices through the model show how grain-size variations were interpolated throughout the basin volume.