Hi, mike - when the daylight hours begin to shorten, that alerts the hens that it's time to slow down & take a break to refuel & prepare for the next laying season. In other words, it's perfectly normal for them to slow way down and stop in the fall. Many folks add supplemental light to their chicken runs/pens to force lay through the off season; I personally don't do this, as I know that it's very hard on them to lay when nature is telling them they need a break. But, I sure don't hold it against folks who DO use this practice.
That might be why I consider my Marans to be good layers; many folks have been commenting that they don't feel they are good layers, but my gals start up before any of my other breeds (usually in late January) and, when other breeds have stopped for the season, mine continue on for several weeks longer. As a matter of fact, I haven't gotten a Plymouth Rock eggs (I have 2 varieties) for almost a month, and my last Giant egg was a couple weeks ago; yet, my Marans are just now beginning to slow down a bit.