Your subject line refers to Groeswen, but your text refers to Groeslon,
which does not seem to be the name of a chapel in the Caerphilly area.
For details of Groeswen chapel, Caerphilly
http://www.genuki.org.uk/big/wal/GLA/Eglwysilan/GroesWen/
See also interesting history on
http://www.genuki.org.uk/big/wal/GLA/Eglwysilan/Chapels.html which also has
links to a photo of the chapel and to a history of it in Welsh (with partial
translation), as well as the list of records held
Note that because of the way that the Archives Network Wales search engine
has been programmed you have to search on Groes-wen to find the chapel
records at Glamorgan Archives in Cardiff, and on Groeswen to find peripheral
information such as a daughter chapel in Rhydfelin. Given that the use of a
hyphen is Welsh placenames is erratic, it is sad that they can't program
their search engine to ignore a hyphen.
The grid reference places the chapel high on the southern end of Mynydd
Eglwysilan above Nantgarw, about 3 miles from Bedwas as the crow flies, a
bit longer going down through Caerphilly and up again.
Groes-wen, Caerphilly CF15 finds it on Google maps and you can see an
extensive graveyard on the satellite image, and a view of the front of the
chapel on StreetView. As the only chapel of the Annibynwyr in the area for
some many years, it is quite possible that people buried there may have
lived some miles away, and maybe worshipped at other Independent chapels
which did not have graveyards, or whose graveyards were full or closed by
public health legislation.
The Memorial Inscriptions were recorded by Glamorgan Family History Society
some time ago on microfiche - as Caerphilly Groeswen *Welsh Congregational
Chapel
listed on
http://www.rootsweb.ancestry.com/~wlsglfhs/fiche3.htm
It you do not have a fiche reader, or access to one, it may be worth
contacting the Glamorgan FHS Aberkenfig Research Centre
http://www.rootsweb.ancestry.com/~wlsglfhs/direct.htm by the email link
there, to see whether (1) the microfiche are on special offer (2) whether it
is possible to supply you with a copy in another format. If you are a member
of Glamorgan FHS you can request lookups in publications.
Jeff