Probably, yes. As Annie pointed out, there are two patterns that are the most likely candidates for what Anonymous was referring to as "Left Rock Turn". One would be a Reverse Pivot-type action, such as the second half of the old Fred Astaire pattern "Fallaway and Rock". The second is the unfortunately named "Left Rock Ad Lib", also a Fred Astaire pattern, which is more of a Hesitation than an actual Rock step.

The "Left Rock Ad-Lib" is the Fred Astaire version of what we call Hesitation Left Turn, and what Arthur Murray calls Magic Left Turn or Arthur Murray Turn. It is not a rock step at all, but a Forward Hesitation followed by 4-6 of a Left Box Turn. In Waltz the timing would be 1(23), 123.

The Fallaway and Rock is as follows:

Typically begin facing diagonal center.

Measure 1) 1-3 Left Box Turn, ending with feet closed in Fallaway position. (Man facing DC against LOD, lady DW against LOD).

Measure 2) Step side & slightly back in fallaway, down LOD, then slip pivot -- same as steps 2,3,4 of an Int'l Fallaway Reverse & Slip Pivot. End man facing LOD.

Measure 3) 3 steps of "Left Turning Rock" (aka reverse Pivots). Complete 1/2 turn over 3 steps to end man backing LOD.

Measure 4) 4-6 of a Left box. End man facing DW.

Regards,
Jonathan