William Black & Eliza Jane Clark. Armagh to Australia

You haven’t said what denomination the couple were. Statutory registration of non RC marriages started in Ireland in 1845. Assuming this couple didn’t marry in an RC ceremony, their marriage c 1850 should be in the statutory records. I searched from 1845 to 1857 but could find no record of it. Could they have married outside Ireland?

Regarding Newton/Newtown, there is a townland named Newtown in Co. Armagh in the parish of Killevy.  Plus there is the town of Newtown Hamilton. In Co. Antrim there is Newtown Crommelin (in the parish of the same name) and Newtown in the parish of Ardclinis.

I can confirm there's no townland called Trimivallen in Armagh. Nearest is Tullyallen. No Black of Clark households listed there in Griffiths Valuation for 1864 though.

Thank you Elwyn for your reply & assistance, The William Black family were not RC.The Black family seemed to have been unassisted immigrants to Australia.Their records are not as informative as those of  assisted immigrants.Some information indicates that William Black was born 1818 in County Antrim although his death cert states he was born in County Armagh .Their marriage seems to have taken place in Armagh & at least one of the children was born in Armagh. We will try to unravel this info.      Thanks again.

If William & Eliza married before April 1845 then their marriage won't be in the statutory records. You would need to search church records, but there are a lot of churches in Armagh, not all have records pre 1845 and of those that do, not all are on-line. The most complete collection is in PRONI (the public record office) in Belfast. But you would need to have some idea of where in the county they lived, to narrow the search a bit. Otherwise you would a hundred or more sets of records to look at.