I have pasted a copy of the thread to a friend in the US who is a fully paid member of the Taffia. :)
She was involved in publishing a facsimile copy of Hanes Cymry America (1872). A History of the Welsh in America by the Rev R D Thomas.
The book has a mention of Racine so I will see if I scan that part.
Coincidentally she lives in Wisconsin.
Blaen y Cae Slate quarry was near Nantlle, again coincidentally my Great Grandfather was manager of the Tyn yr Weirglodd quarry at Tal y Sarn but that was later after 1900.
My family were PARRY
Have a look here on the database of the Royal Commission of Ancient and Historic Monuments of Wales.
http://coflein.gov.uk/en/site/search/result?FREETEXT=blaen%20y%20cae&SEARCH_MODE=SIMPLE_SEARCH&SEARCH_TYPE=ALL It will also take you maps showing the locations.
You can also see maps from the mid 19th Century of the area on the National Library of Scotland website.
http://maps.nls.uk/ The 25" coverage has not reached Wales yet
Ordnance Survey, 25 inch, England and Wales (in process) - 1841-1952 - 67,941 sheets
Ordnance Survey, Six-Inch, England and Wales - 1842-1952 - 37,390 sheets
Ordnance Survey, 1:25,000 maps of Great Britain - 1937-1961 - 2,027 sheets
By the way, it is Caernarfonshire or sometimes Carnarvonshire or Sir Gaernarfon.
A warning, Welsh names are patronyms so another Roberts family will not necessarily be related to your one though I also have Roberts in my family around there.
Gwynedd Archives seem to have references to Blaen u Cae
https://diogel.cyngor.gwynedd.gov.uk/DATRhagorol/Chwilio.aspx?iaith=en For examples
X/Dorothea/1085
DRAFT REPORT on the Talysarn Quarries: Blaen y Cae, Twll Mawr, Cloddfa’r Coed, Tanrallt
There is a Nantlle area website
http://nantlle.com/home.htm
Martin Briscoe
Fort William