New results are presented for the behavior of viscoplastic, aqueous polymer gels of Carbopol 940 when subjected to vertical, mechanical vibration. The vibrations were at frequencies in the range 40-100 Hz, and at accelerations of 5-35 times that of gravity. It is shown that, upon vibration, samples form persistent holes in a regular, geometric pattern. Because the gels are viscoplastic, the holes persist even when vibration ceases. Depending on the sample mass and vibration conditions, 1-7 holes form at regular angular intervals, and at a constant radial distance from the sample center. Increasing the sample mass can lead to the formation of a second ring of holes, at a larger radius, and at angular positions midway between those in the inner ring. The holes form reproducibly over a range of accelerations, with the critical acceleration for the onset of hole formation increasing linearly with the vibration frequency. Qualitatively the hole arrangement is surprisingly similar to two-dimensional surface shapes derivable from lubrication theory of a Newtonian fluid that has been modified to include a destabilizing rheological hysteresis in response to the vibration. (C) 2014 Elsevier B.V. All rights reserved.