An abstract from GSA Today might be of interest:

Historic records refer to Rhakotis as a settlement on Egypt's Mediterranean coast before Alexander the Great founded the famous Mediterranean port city of Alexandria in B.C. 332. Little is known of Rhakotis, however, because the site has yet to be clearly identified beneath the modern city. This problem motivated a geoarchaeological investigation of sediment cores from Alexandria's East Harbor, from which radiocarbon-dated sections of pre-Alexander age (>2300 yr B.P.) have been obtained for study. These core sections comprise a number of critical components, five of which are emphasized here: ceramics, rock fragments derived from Middle and Upper Egypt, and sediment with markedly increased contents of lead, heavy minerals, and organic matter. A multidisciplinary approach, by which archaeological, stratigraphical, petrological, and geochemical methodologies are applied to study the five distinct core components, reaffirms that a sum can be greater than its parts. Together, the diverse markers in the dated core sections enable us to confirm human activity to at least seven centuries before B.C. 332 on the mainland coast, where Alexandria would later be established. Alexander's city, it now appears, rose from a pre-existing town whose inhabitants had long before recognized the favorable harbor potential of this Egyptian coastal sector. The discoveries, providing direct evidence of the settlement's early (to ca. B.C. 1000) existence, are intended to prompt new exploratory efforts on land and offshore to further delineate that center's actual position and history.

... a PDF of the whole article can be downloaded from the original abstract page.

Okay, I've read it in its entirety and it's not a bad article, although I do not know how they distinguish between 'cores related to settlement' and 'cores related to stuff that's washed down the river'. Whatever the case, though, I do have a major stylistic problem. Near the beginning the article says:

Historians generally agree that Rhakotis, or RĂ¢-Kedet, was
a settlement established before the fourth century B.C. in the
area subsequently developed as Alexandria. Rhakotis has been
vaguely alluded to as a modest fishing village of little signifi-
cance, a more substantial walled center, or possibly a fortified
settlement (Fraser, 1972; Empereur, 1998; Baines, 2003; McK-
the markers in the dated core sections enable us to
enzie, 2003; Ashton, 2004).

The conclusion, however, suggests:

In summary, evidence from East Harbor cores shows that
Alexandria did not grow from a barren desert, but was built
atop an active town that had for centuries exploited the safe
harbor setting along this Egyptian coast.

Usually one sets up a straw man before knocking it down, but nowhere in the article is the suggestion made that Alexandria DID arise out of nothing. The only reason I bring this up is because this is an oft-mentioned "claim" supposedly ascribed to Classicists when 'discussing' things with Afrocentrists about the Library of Alexandria. As mentioned, that there was a settlement of some sort there prior to Alexander is acknowledged by Classicists and appears to be confirmed by the above study. What remains to be seen, however, is whether the study in GSA will lead to more studies which can give an idea as to the extent of the pre-Alexandrian settlement at Rhakotis (and indeed, the authors do hope that it does lead to further studies).