Sorry but these distant photos were taken at waters level, the heat distortion was pretty bad but with Ziess 85mm scope and fixed 40x lens, the following details were seen well over a 3 hour period.

First the white face showed just a thin black cap over the crown, but between these 2 grebes facial patterns can be very close in winter pumage, with this bird the white was very evident over the eye, leading me to gather more points for a Clarke's ID. The line of black down the back of the neck was pencil thin at the nape and the white cheeks were easily seen, the body color was not jet black, the bird's sides were extensively grayish and last but not least, the bill shown clear bright yellow, all adding up to a rare eastern Clarke's ID.