Hi- I'm not a builder but have helped pour foundations a few times: isn't that just leftover cement from the bottom of the forms?

How old is your house?

The house is 90 years old. There are two rooms in the basement that have a higher concrete floor poured so I’m wondering if this is just bringing up the other walls to the same level?

The first solution to wet basements is getting water away from your house through gutters and, if necessary, piping it far from the house.

Is it a rubble foundation (rough stones mortared together, not regular rectangular blocks)? We have something similar on our 1915 house in certain spots - our best guess is that it is some sort of (amateur) lateral reinforcement, but unfortunately we don't know for sure.

It's possible, though unlikely, that it could be a footing.

Thanks all, yeah I think it’s just the footing, or somebody tried to stop the water in the ist by putting in this extra concrete.

Regarding the water, I’ve resealed the driveway that goes along the house to direct water away. Next step is probably an internal French drain.

Before you put in a french drain, read "5 steps to a dry basement" by Ron Gay. Water issues often start outside the house (bad grading, leaking gutters, etc.) and can often be solved most cheaply by exterior measures.

Thanks for the suggestion. I’ll definitely take a look.

Problem is we are in the city with neighbor close by, lots of concrete around, so there’s not too many places where water can go. But it’s good suggestion. I should probably investigate outside a bit more before biting the bullet on internal drain.

French drains can certainly be the right solution sometimes. The problem is that "basement solution" companies have a vested interest in selling you an expensive solution, whether or not it is the right solution.

Sometimes plants can have an impact, too - a colleague had flooding after his neighbor cut down a stand of arbor vitae that had been drinking a lot of the groundwater.

Interesting, I’ll definitely go check out the outside again and observe a few more times when it’s raining