Need confirmation on this one: The marriage and children on the Phifer marriage may be incorrect and do not match the research of David Eggler. The concrete link between Issac/Jemima also needs to be substantiated.

1840 Census - Benton County MO, Isaac Jones. married with two children.

Possible Obit - Died: At San Jose, Upper California, of cholera, on the 28th of November last, Mr. Isaac N. Jones, formerly of Missouri, aged about 36 years. The deceased was a native of this county, but emigrated to Missouri some years since, which state he left about a year ago for California, where he ended his earthly career.
Saturday, Jan. 18, 1851105

Isaac N. Jones and William R. Roberts were the next to "hang out shingles " in London. The former came from Tennessee, and was Prosecuting Attorney in 1837-38. In the fall of 1840, he went to Philadelphia, and engaged in merchandising. Thence he removed to -Missouri, where he followed his profession with considerable success. While in London, he married a daughter of George Phifer, a well-known pioneer of Madison County


From the research of David Eggler:

Isaac N Jones practiced law in the 1840s and, perhaps, in the late 1830s in Platte and Clinton Counties, which are both in far western Missouri. In 1840 two men named Isaac Jones, with families, lived in Clinton County and one in Cole, Benton County. The first Circuit Court of Genry County was held in Athens on March 12, 1846, with Isaac N Jones as circuit attorney. In July, 1848 Isaac N Jones defended himself, in the Missouri Supreme Court (googlebooks), concerning his acting as a collection agent; the complaint was filed in Platte Circuit Court. Email from Margaret Meacham Wiebusch says that the family moved to California in 1848, where he died.
The story Frances Puckett Goes to Ohio [Los Gatos Daily Times 11-30-1953] says the family left Savannah [Andrew County, two counties north of Platte County, and which contains Benton and Platte Townships], Missouri to come to California in 1850. "Grandfather Isaac Newton Jones was a lawyer and a circuit judge. He came to California, and to San Jose, to defend his brother's right to a 12,000 acre Spanish grant. He settled in San Jose and built his law office where the Auzerais building now stands. But the family's history was hard and tragic. They set out for California with 100 head of cattle. They traveled in a covered wagon, and the two oldest sons rode ponies to hold the loose herd together. The family found the travel rugged and rough. They were attacked by hsotile Indians and overpowered. Isaac Newton Jones was, however, a linguist, and spoke seven languages, including the Indian dialect. he talked to the chief of the attacking tribe, and convinced him that massacre would benefit him not at all. The Indians accepted a large portion of the Jones' cattle and departed peacefully.
With their food supply thus depleted, the remainder of the journey was still more trying, and before the hungry family arrived in San Jose they had slaughtered one of their ponies to feed themselves. Upon arrival, Grandmother Jones was very sick. Her ailment was described as a bad cold, and Isaac wrote to his brother in the Santa Cruz mountains that he expected her to die at any moment. It was not Grandmother Jones who died. Within 24 hours of the time Isaac posted his sad letter, he was dead, and his eldest son, William, was also dead. They died of cholera. Grandmother Jones rose from her sickbed and gathered her three children, Julia 14, Leon 11, and Worth Walter Jones 2 (who was to become Frances Abbey Puckett's father) about her and announced 'I'm going to open a boarding house for the gold miners!' She opened her boarding house and charged the miners $10 per day. In two years she saved enough to send her two boys back to Pennsylvania to live with her sister, Mrs Grace Whiteman [sic]."
From a London (Madison County, Ohio) newspaper 1-18-1851 (http://jones-seattle.org/WebCards/ps04/ps04_117.htm):"- Died: At San Jose, Upper California, of cholera, on the 28th of November last, Mr. Isaac N. Jones, formerly of Missouri, aged about 36 years. The deceased was a native of this county, but emigrated to Missouri some years since, which state he left about a year ago for California, where he ended his earthly career." Once tied to Madison County, Issac can be tied to the genealogy developed by Douglas S Jones (jones-seattle.org/WebCards), for which see notes on Isaac Jones, the probable father of Isaac Newton Jones. The History of Madison County (on heritagepursuit.com) has this interesting sentence: "Isaac N. Jones and William R. Roberts were the next to 'hang out shingles' in London. The former came from Tennessee, and was Prosecuting Attorney in 1837-38. In the fall of 1840, he went to Philadelphia, and engaged in merchandising. Thence he removed to Missouri, where he followed his profession with considerable success. While in London, he married a daughter of George Phifer, a well-known pioneer of Madison County." This sentence fits Isaac N Jones except for the person he married. Either there were two attorneys named Isaac N Jones who went from Madison County to Missouri, or the account has the incorrect name of the wife; his probable brother William did marry a Phifer.
If Isaac Newton Jones was the son of either Isaac or Zachariah Jones, who arrived in Ohio in 1815, then he was most likely born in East Tennessee.103