Þau Sveinbjörn ok Steinunn áttu tvá sonu ok fimm dætr. 

They, Sveinbjorn and Steinunn had two sons and five daughters.

Herdís hét dóttir þeira, er átti Hallr prestr ok lögsögumaðr, sonr Gizurar lögsögumanns. 

Herdis was the name of one of their daughters, and Hallr married a priest and lawyer, a son of lawyer Gizurar's.

Helga hét önnur dóttir þeira. 

Helga was the name of another of their daughters.

Hana átti Brandr Þórisson ok Helgu Jónsdóttur austan frá Svínafelli. 

She married Brandr, son of Thoris and Helga (daughter of Jon), fron the east beyond Svinafell.

Guðrún hét in þriðja dóttir þeira. 

Gudrun was the name of their third daughter.

Hana átti Sámr prestr Símonarson. 

She married priest Samr, son of Simon.

Halla hét in fjórða. 

Halla was the name of the fourth.

Hana átti Þórðr Arason. 

She married Thordr, son of Ara.

Birna hét in fimmta. 

Birna was the name of the fifth.

Markús hét sonr Sveinbjarnar inn ellri, en Hrafn inn yngri. 

Markus was the name of the elder son of the Sveinbjarns, and Hrafn the younger.

Markús var mikill maðr vexti ok ramr at afli. 

Markus was a man large in size and strong in body. (Apparently, "ramr" = "rammr"?)

Svá var handleggr hans digr meðal axlar ok ölnboga sem lær manns væri. 

So were his arms big between his shoulders (I must have the translation wrong here as arms aren't between shoulders!) and elbows a man's thigh would be.

Hann var ungr til bókar settr ok síðan vígðr til prests. 

He was set to learn (at a) young (age) and then concecrated as priest.    (Z. setja 11: s. e-n til bókar, to set one to learn)

Á Eyri í Arnarfirði stendr steinn, sá er Markús bar þangat. 

At Eyri in Arn's-firth stands a stone, the one that Marku carred there.

Í þeim steini váru klappaðir fjórir koppar. 

In that (isn't "þeim" plural?) stone were hammered four coppers ("pieces of copper").

Síðan er hann hafðr til þváttsteins ok er svá höfugr, at varla megu fjórir karlar hefja. 

Next he used it for a washing stone, and it is so heavy that four men can scarcely lift it.

En fyrir því at skömm eru áföll þessa heims, þá varð Markús eigi langlífr. 

But before becuase a shame were these visitations at home, then Markus was not long-lived. (???)

Hann fór einn vetr ór Arnarfirði um heiði til Tálknafjarðar ok þeir fjórir saman. 

He travelled one winter out of Anarfirth across a heath to Talknafjard, and the four together.

Ok á heiðinni gerði at þeim vánt veðr, svá at þeir fóru villt. 

And at the heath they got some bad weather, so that they went astray.

Ok er minnstar vánir váru, þá brast undir þeim einn hengiskafl, ok í þessi skriðu týndist Markús prestr ok annarr maðr með honum, en sá komst í brott heill ór skriðunni, er óknástr var. 

And when it was less bad (plural in OI), then failed under them a certain jutting heap of snow broke under then, and in this forward movement the priest Markus and another man with him perished, and so escaped sound out of the jutting heap of snow, which was the weakest.

Sá hét Árni, ok Húnþjófr hét annarr maðr, er á brott komst. 

One was named Arni, and Hunthjorf was named the other man, who escaped.

Þessi atburðr varð þar, sem heitir Feitsdalr.

This accident was there, where it is called Feitsdale.