Whoa! I really think this stage is sooooo craggy and ugly. Cannot wait until they feather out, but these 3 week old ISA's won't be pretty for quite some time. Love the adult look, but until then.... whew.
Good eye. Red Rocks X is the "other". Black Star is a name also used for that cross of Barred Rock/RIR.
The 15 ISA Browns are a first for me, this year. The manager of a local Family Farm store practically gave them to me. I know they are the egg laying queens, but we shall see if their temperament is to my liking. I grew up with White Rocks and still have an affection for the Rock family.
Reminds of when wife first started raising chicks. She asked me to look on the internet to find instructions on how you separate boys and girls. So I entered "Sexing Chicks" on Google. Brought up some verr-rr-y interesting results, especially with the wife looking over my shoulder!